On the Origins of NihonTo

On the Origins of NihonTo
An attempt of interpretation of NihonTo evolution
by Carlo Giuseppe Tacchini
Firstly published on JSSUS Newsletter Volume 41 n. 5
October 2009
Updated and extended version
Acknowledgements
First acknowledgement must be given to Dr. W.W.Farris for his kind permission to use parts of his
works and for the bibliography. Then to all the authors quoted in the sources‟ list and the ones ,
especially Masakuni, that with their works have enabled an armchair student to explain his own
opinion. I must mention Boris Markhasin for kindly providing material on Jokoto complex construction and Dr. Moriyama Koichi for suggestions about the meaning of some difficult passages and
words. A special acknowledgement (and huge thanks) to Markus Sesko, which collaboration, information, translations of a lot of material on early Japanese swords and swordsmithing have
been invaluable to me. Last but not least John A. Stuart and Barry Hennick for proofreading my
especially poor English and Ken Goldstein, (Ph.D) for professional feedbacks and proofreading.
Disclaimer
All mistakes, misconceptions, misunderstandings or plagiarisms are surely mine and I take full
responsibility of them. Just remember that this work is not intended for commercial purposes and
still remains simply an armchair student‟s effort.
I think to have been fair in using sources giving full credit to Authors and listing all pictures‟ provenance on separate indexes but if anything in this work is not considered “fair use for study reasons not related to commercial purposes” and copyright infringement is a source of problems to
anybody might be concerned, please contact me at [email protected] in order to arrange the matter. The same e-mail address will welcome any suggestion or input about this work-in-progress.
For the agreements taken with the sources I've been able to contact and the persons mentioned
in acknowledgements, no part of this work can be used for commercial purposes. Any other use
admitted with credit to the original source, either me or the authors quoted in bibliographic notes.
ON THE ORIGINS OF NIHONTO
By Carlo Giuseppe Tacchini
“Form follows function” - an old mantra for swords enthusiasts that has proved to be effective.
“To understand Japanese Sword you’ve to know Japanese History”, by Fujishiro if I recall
correctly. These two simple statements are at the heart of this article.
Introduction
Nihonto are today regarded by high-end scholars and collectors exclusively as artworks. In their
original historical context they were weapons. World War II and the propaganda that followed almost caused the extinction of the art of sword making.
This resulted in many Nihonto texts lacking an exhaustive explanation of the genealogy and development if the Japanese sword as we know it. Its appearance is today regarded as a sudden,
almost “traumatic” occurrence in the second half of the Heian Period, somewhere between 900
and 1100 C.E. (earliest dated fully-developed Nihonto being a Yukimasa dated 1159 C.E.)1. This
blade has the three key characteristics of a Japanese blade - sori, yakiba and hada. Modern
tachi entered the scenes of Japanese palaces and battlefields replacing the Chokuto of continental design passing through Kogarasumaru and Kenukigata zukuri; but was this transition really so
simple? Curiosity and love for history made me wonder how such an advanced engineering as
the one we can find in modern tachi could have developed and evolved in ancient Japan. The
poor results of a search of English texts led to a search of academic studies on ancient history
and Japanese texts on early Japanese weaponry. Cross referencing these sources led to this
work. The fact that the establishment of the first fully developed Nihonto and the establishment of
the Samurai class are placed in the very same timeframe suggests that there is a possible link
between the common explanation of Nihonto development and the old theory about the rise of the
Samurai as a social class. This theory is called the “Western Analogue Theory” 2.
Assuming that the European historical development was paradigmatic; Japan, after having
adopted the continental institutions with the Taihō codes in 701 C.E., which compares to Roman
institutions in the West, was forced by their failure into a period of anarchy by year 900 C.E. This
lasted to 1100 C.E. and resulted in the creation of private estates as entities of economic growth
protected by a new class of fighters, the Samurai. This compares with the rise of the European
Feudal System. The establishment of the first Shogunate in 1185 was the crown of the process.
Nowadays the whole historical process is regarded as a more evolutionary one, hence the
“Evolutionary Thesis” has replaced the old one in many historical key passages. 3 But, if the rise of
the Samurai class has been revised from the one “en vogue” in the „60s, we can‟t say the same
for the theories about the development of Nihonto. It‟s not the task of this work to discuss the differences between “Western Analogue” and “Evolutionary” theories about the rise of the Samurai.
In this article the “Evolutionary Thesis” will be applied to both Japanese history and the development of Nihonto. The aim will be to lead to the fixing of the final shape and the features of fully
developed Nihonto.
Requirements of a Nihonto
Although the term Nihonto is inclusive, in this article Nihonto will mean swords as defined as fully
developed when considering geography, artistry and technical aspects.
Geography
- Provenance, meaning the sword has to be made wherever in Japan but not imported, even
when of continental design.
Artistry
- Hada, that has to show patterns of layered steel
- Yakiba, that has to be present as evidence of differential hardening - Hataraki
- Sugata, that has to show a curvature.
Technical
- All the above
- Shinogi, a ridge line - often inferring the presence of a functional yokote.
- Shingane, the presence of a complex construction with different steels to improve shock resistance
In the modern world of collectors, not all of the above requirements are needed to be present together in the same blade at the same time in order to consider it a Nihonto. Applying the same
requirements with a view to trying to explain the appearance of each feature that leads to our current view of Nihonto is the main goal.
Historical background from 300 B.C. to 701 C.E.
The Sino-Korean influence and the introduction of the concept of
Counter-response and symmetry
Counter-response and symmetry is a term used to explain the process in which an antagonist
reproduce the same kind of weapons and tactics used by the enemy he is fighting against or he
had experience of fighting with, because such weapons and tactics proved to be effective. 4 The
development of weapons is strictly related to the development of strategies and technologies; so
to follow the evolution of the sword linking military technologies and tactics to the people for
whom these were made is a must. Around 300 B.C.E. Japan entered (almost…) simultaneously
both the Bronze and Iron Age. The Japanese soon adopted “Counter Response and Symmetry”
replicating continental bronze weapons. The smelting of the first iron arrowhead is fixed at the eve
of Christian Era5 and by the end of 1st century C.E. blacksmiths, either native or immigrated, were
producing iron swords in Japan6. Significantly, the same date is given for the first archeological
evidence of war victims found at Doigahama, Honshu.7 The arrival of farming created differences
amongst populations and poorer begun to attack neighbors for food and war spread all over the
country . It soon was evident that the supply of iron was a problem. Indigenous production was
too low in Japan untill the late Kofun with the introduction of the Tatara. Supply of raw materials
has been suggested as the main reason for the Japanese becoming involved in politics on the
Korea peninsula in the 4th century8. The Japanese military had significant inputs from wars between Yamato-Wa, Silla, Paeckche and Kogŭryŏ. These inputs came either from expertise of immigrants (especially with a first great flow of immigrants after the destruction of Kaya States in
562) or from direct experience of fighting on the peninsula.
Amongst them, the most important was surely the use of
horses for fighting. Back then horses were expensive and of
little use other than for war. Therefore civilized societies that
used the horse extensively tended to have specialized fighters9, usually wealthy enough to provide them with such a
costly weapon. Secondly the lightly armored mounted archer
who used both bow and sword became the Bushi. Notably
the stirrup evolved in the 6th century.10 According to the Kojiki, a Korean blacksmith named Takuso was brought to the
imperial court from Paeckche during the reign of Emperor
Ojin. There are no firm dates for his reign, but he is the oldest of the emperors in those chronicles whose existence is
accepted as having been real and a dating to late 4th century
C.E. and might be an acceptable hypothesis. The Kojiki also
tells of an exceptionally talented blacksmith from Silla who
was employed by the court in the 12th year of the reign of
Emperor Bidatsu (583 C.E.). It was he who provided instruction in the techniques of smithing.
Fig. 1
In these early periods (300-500 C.E.) the ceremonial swords were, generally, either straight and
double edged, much like the well known Ken that resembled the ones of the Late Chou Dynasty, or snake-like “Meandering Swords” (Dakô-ken). Early examples have a ring-pomelled
tang. This ring later moved to the mounting as one of the fittings. The cover of the catalogue by
the Suwa City Museum11 shows all three of these blades/features. Note that these three are not
to scale.Many swords have been excavated throughout Japan, starting from Kyushu, and many
from what the ancient sources call the “Eastern provinces”. The term “Eastern Provinces” back
then meant the Kanto plain and northeastern Honshu, well-suited for horse breeding. The story
of Prince Yamashiro and his rebellion to the Court tell us that most of the royal retainers
(Toneri) originated and were hailed from that area12. Kanto already had a strong military and
economic base, and its importance was rising at the eyes of the Court after the fall of the Korean allied Kaya States in 562 C.E. 13 There is no consensus on how much the Court power
was effective here at this stage of Japan‟s history or about the ethnicity of “Emishi” (see appendix 1). It is suggested that the Kanto could have been a politically independent region. It was
fairly advanced in both weapons and fighters for the period‟s standard. The Kanto was not necessarily subjuMap 1
gated by the Yamato Court but
rather served it
as a vassal.14
Most
scholars
agree that the
Kanto
already
had his own well
defined identity,
as suggested by
the use of specific geographical terms like
“Eastern Provinces”
or
“Azuma”
(The
East), and also
had a special
military importance by year 600 C.E. A sword dated to this period and similar to the one in fig. 2 bears extremely important inscriptions showing Chinese characters used to write at least a few Japanese words. This linguistic evidence is still highly debated and need further studies. This blade
is identical to continental specimen and might be an imported one with inscriptions added later.
Another possibility is that a Korean immigrant might have made this sword as Korean linguistic
elements are also found in the same inscription15. The Sui (589-617) and Tang (618-907) Dynasties had an aggressive politic that lead not only to the unification of China but also to a pressure against the Korean States, invading them in the 630s. Japanese were aware of what was
happening as they still had strong interests and ties with Korea. Surely they wondered about the
intention of Chinese armies to invade Japan. It is now believed that the anti-Soga conspiracy
and assassination of 645, known as Isshi incident, was aimed to give to Japan a new ruler able
to catalyze the consensus needed by the hard times16. Prince Naka who focused on military
affairs was that ruler. Kanto and Mutsu were divided into 8 regions. Soryo (governors) were sent
to strengthen the Court‟s control17 and to rule the regions. These governors were recognized by
lawgivers as a distinct entity18. Armor and swords were collected into government ruled arsenals.
Fig.2 From Funayama Tumulus, Nagomi Machi, Kumamoto, Kofun period, 5 th/ 6th century, National
Treasure, Tokyo National Museum
No one was allowed to own them unless directly involved in the defense against the “Emishi”,
eastern barbarians or “disobeying people”. The new Emperor promulgated the Taika Reform
Edict, a keystone event in Japanese history .The authenticity of the Edict is now debated but
two provisions of Articles 1 and 4 are considered legitimate and related to this work 19 .
(Article 1) … Let… Border Guards … be provided…
(Article 2) As to weapons, each person shall contribute a sword, armor, bow and arrows, a flag
and a drum…20
The Border Guards were provided by Eastern Honshu to protect the supposed target of a Chinese invasion, Northern Kyushu. Flags and drums are implements intended to coordinate
troops movements in what were continental tactics of mass peasants infantry armies that, evidently, started to be used together with the mounted archers. In 645 in order to reinforce the
Court‟s control on eastern Provinces, growing fast in military importance, orders of collecting
private weapons in such Provinces were issued21. On the continent things went from bad to
worst and the Tang armies, after having attacked Kogŭryŏ proceeded against Paeckche. Silla
entered the war too, on the Tang‟s side22. Now Japan‟s Court had to take steps in the attempt to
stop the tide away from their shores and sent 3 expeditions in aid to Paeckche from 661 to 663
A.D., using a traditional approach, so fighting technology and tactics were the traditional ones,
not following the continental example, yet, even after two decades from the attempt to introduce
continental institutions. Soldiers for the expeditions were mainly hired from Kyushu and Western
Honshu23 . After an initial draw on the battlefield the Tang fighting tactics proved to be decisively effective at the final battle of Paekch‟ŏn River, that according to Korean and Chinese
sources cost the Japanese thousands of men and horses24 and is still regarded as one of the
worst defeat in Japanese history. Disunity and fighting tactics based on individual skill and
proud were no match for the more numerous, better armed and better drilled Tang armies, well
coordinated by capable generals using formations of infantry “en-masse”. 668 A.D. found all of
Korea under hostile control, meaning the end of one hundred years old Japanese foreign policy,
relying on continental relations with Paeckche against Silla.
The Court was moved to Ōmi on Lake Biwa, to stay at a distance considered safe enough from
continental invasions. The usual sea trade routes were now no more reliable and the iron supply
from Korea was harder to get in order to increase the internal production. Import of swords was
affected too. This possibly forced the Japanese to enhance their iron production and smithing
technical skill thru the help of immigrants. The events on the peninsula created a flow of Korean
refugees with artisans, engineers and people with any kind of knowledge and skill to enter Japan and the capacities of these men had to be of high quality if they were allowed to contribute
to fortify Kyushu (Farris suggests these fortifications were the basis for later Dazaifu) and all the
way thru Ōmi with Korean-style fortifications against the supposed ongoing invasion from Tang
and Silla allied forces. Board Guards garrisoned Tsushima and Iki islands. Again, counterresponse and symmetry took place, with the need of further changes in the military organization
thru the first general census in 670 A.D. A reliable census is a must in order to organize a conscript army as the one that was in the projects of the Court 25. The Paekch‟ŏn River defeat had
also political consequences. In the struggle for replacing Tenji, that was no more “in auge”
amongst the vital military èlite of local strongmen (Kuni no Miyatsuko), Prince Ōama was able to
defeat Prince Ōtomo for having denied him access to the military resources of Eastern Provinces through the blockade of Suzuka (Ise) and Fuwa (Mino) passes and being able to raise
mounted troops in these Provinces rich in weapons and soldiers26. Prince Ōtomo too benefited,
at Kurafu battle, from the valor of a contingent of mounted troops that had immigrated from the
Eastern Provinces27 , a further evidence of the military importance of the Kanto as a source of
skilled mounted fighters. In 673, Prince Ōama became Emperor Temmu, the Emperor that
started to ferry Border Guards from the Eastern Provinces to Northern Kyushu on a regular basis28. Later, to improve and enhance the military value of Kanto the Court sent specialists on
Chinese tactics based on Sun-Tsu‟s “The Art of War” and other classics29 and established government-controlled pastures for military horse supply30.
The Japanese sword in early stages: IVth-VIIIth century
Shinogi, Hada, Shingane and Yakiba enters Yamato.
In Japan from IVth to VIIIth century C.E. there were the same types of swords we can find in
China from the Jin to the Tang Dynasty (265-907 A.D.). The trade/cultural/diplomatic relations
between the two countries were both direct and indirect thru the Korean states. Early swords
introduced when Japan entered bronze/iron age are of models already established and evolved
on the continent, where the ridged types were gaining an increasing popularity. Differences
soon begun evident in the mountings rather than in the blades, that needed little to no changes
as they fit well the purposes of actual combat tactics either still too primitive or (after the battle
of Paekch‟ŏn River) mirroring the Chinese model of maneuvering mass infantry. The use of
mounted archers, even if quite common, hasn‟t affected the sword shape yet, as seems the
straight, single edged model fulfilled well enough the needs.
Early swords typologies
Fig. 3 Different lengths and tangs for each type have been found. In black the cross-section of each part.
__________________________ 30 cm / 11,81 in
In Japan the length of found specimens vary, the longer being even more than 1 meter and the
shorter around 60 cm. Anyway the majority are in the range of 60s-70s cm, length that should
put them into the category of utilitarian weapons rather than court or ceremonial ones, as most
likely the difference between the two types might have been in the mounting rather than in the
length. Dakô-ken, the “meandering sword” as far as I know is found only in Japan and is purely
ceremonial. Picture n. 3 shows the models used in this span of years, evolution being from top
to bottom, even if possibly not entirely correct, either in chronology and surely in proportions, as
different models, with different lengths for each model, co-existed in the same periods for some
time. First thing that attract our attention is the progressive appearance of a ridge. Smithing
technologies increased thanks also to the flow of immigrants not only from Korea but also from
China due to the political situation after the collapse of Eastern Jin dynasty, during the Northern
and Southern Dynasties, a period of both problems and notable technological advances as the
stirrup. The Shinogi (ridge) first appeared in China at least during the Han dynasty and entered
Japan as soon as the trade allowed it. Shinogi (ridge) is a natural addition to the flat (Hirazukuri)
blades in order to obtain a more performing sword and is mainly intended for long and medium
blades. It firstly appeared in Kirihazukuri blades, the same as in fig.4. These blades has the advantage in having a thicker and consequently heavier and more resistant body maintaining a
thin, hence sharp, edge thru the application of an angle. The
result is a 5 sided cross section. This is a very good enhancement for swords that might strike hard objects as armor or bones. A thinner triangular section (Hirazukuri) is
sharper but also more prone to break due to the shocks
mentioned. More, the beefier upper section of Kirihazukuri
gives more weight to the kinetic action, and this possibly
remedied to the lesser cutting ability. With time swordsmiths
realized that to move up the Shinogi would mean to add
sharpness to the edge, in some way mixing the Kirihazukuri
(upper part of the blade, above the Shinogi) and Hirazukuri (lower part of the blade, below the
Shinogi) maintaining a five sides cross section. This proved to be the more effective cross section for long blades in Japanese history, with a perfect mix of resistance, weight placement and
cutting ability. In this work I can‟t discuss the Niku (“meat”, a curvature in the angled section that
improves cutting ability and edge resistance to wrongly angled cuts) because of lack of material
in reference to pre-Heian swords. Image shows at left (A) Kirihazukuri cross section, at center
(B) Shinogizukuri and at right (C) Hirazukuri cross section.
Hada and Shingane
Hada (texture) is the result of folding and hammering (Tanren) the steel bar during the forging
process (see fig.4). This ancient practice has been developed in China where was present at
least from the early Han Dynasty (IInd century b.C.). It serves primarily the purpose of refining
the steel from impurities that gets pushed out from the heated bar by the repeated folding and
hammering actions. The practice has been imported via the already mentioned ways and later
evolved and has been developed to the point that it allowed the smiths to be able to achieve
many different types of textures that appear in different parts of the blade according to the way
the steels were folded and how the blade was assembled. These textures, often mixed in different compositions, are often specific features of a given school and a precise Kantei
(appreciation) point. Shingane (Inner steel) is a term used when the blade has a complex construction, implying usually at least two different bars of steel. I‟ll give a better explanation later,
but for practical reasons I‟ll not split the discussion into two different chapters for Hada and
complex construction/engineering of the blade.
Fig. 4 Han Dynasty ringpommelled sword found in
Duan River (China) and
polished by Prof. Min Yan,
showing early type of Hada.
A proto-shinogi and protoyokote, forward-angled , are
also present.
Chinese swords that were made of folded steel were referred as “Thirtyfold”, “Fiftyfold”,
“Eightyfold”, “Hundredfold refined steel”, and according to D.B. Wagner the swords unearthed
in Eta-Funayama (“Eightyfold Refined”, Vth c. C.E.) and the one unearthed in SakitamaInariyama (“Hundredfold Refined”, 471 or possibly 531 A.D.) have been forged in Japan 31 .
Wagner gives also a very interesting explanation of the meaning of “Thirtyfold” and “Fiftyfold”
discussing the cross-section of two Chinese blades of the Ist century C.E. that show definite layering in the microstructure. The sectioned blades show that they are composed of three regions : a central section of about 2mm of thickness and two “mirrored” side sections of about
1,5 mm thickness. The side sections are made of alternate layers of respectively 0,4 and 0,6 %
carbon content while the central region is uniformly of 0,7/0,8% carbon content 32. Wagner reports a very interesting hypothesis on how the number of layers were inscribed on the blade
due to the rules of “quality control” adopted in China (and possibly in Japan too if we accept
Wagner‟s opinion about Inariyama and Funayama swords as forged in Japan, even if not necessarily by japanese smiths), has a practical explanation after the microstructure analysis. The
inscription might state in an approximate (but very close) way the number of layers rather than
folds (interestingly, to Nihonto enthusiasts the misuse of the term “fold” instead of “layer” is not
new). Using the “Fiftyfold refined steel” sword example with a Sanmai (three – sections) lamination method we may infer the following sequence :
- A bar of high-carbon steel (0,7/08 %) is folded 4 times giving 16 layers. This is the edge
hard steel.
- One bar of low-carbon steel (0,4%) and one bar of medium-carbon (0,6% ) steel are
welded together .
- The resulting bar is further hammered and folded three times, giving a final 16 layers. This
is the softer steel that will be either the jacket or the core of the blade according on how
will be performed the next passage.
- The softer bar is wrapped around the harder one. The sword will be made hammering the
resulting bar and as the wrapping will leave the harder edges (the blade in question is a
double-edged jian) outside we‟ll obtain a 16 (left side) + 16 (core) + 16 (right side) totaling 48 layers. Very close to the figure of “Fiftyfold”. Following the same procedure we
can infer that “Thirtyfold” should be 8+8 (soft) + 16 (hard) = 32. “Eightyfold” 8+8 (soft) +
64 (hard) = 80. “Hundredfold” 16+16 (soft) + 64 (hard) = 9633.
Fig. 5 Left : Picture of the actual blade,
Top right, high-res picture of the layers,
bottom right Wagner‟s rendition of the
above discussed Jian (two-edged
swords) cross section of the layers.
Another interesting example of
complex construction has been
found in Korea. A chisel excavated in southern Korea dated
from the third century B.C. to
maximum the third century A.D.
has pure iron at its centre and
an outer layer of steel with
0.81% carbon and 6.31% silicon. This silicon content is surprising; modern iron rarely has
over 2% silicon, and one generally finds even less in ancient
iron. It is suggested that this
chisel was carburized by dipping
it into molten cast iron.34
Even if this “per sè” doesn‟t enforce the theory of early use of shingane in swords, it tells us that
the idea of a complex construction to absorb shocks was considered useful not only for military
purposes, supporting the theory that this idea is older than supposed.
Returning to Japan, however, Dr. Honma Junji, in discussing the swords preserved in the Shōsō
-in” states :
“seem however that they, unlike later swords, do not have the Shingane (“core steel”) added
inside. They were probably made by hammering the Kawagane (“skin steel”) flat and folding it
lengthwise, with the edges meeting at the mune (back) for cross sections (sectioned parts) of
swords unhearted from proto-historic tombs (Kofun) frequently show such construction”. 35
and that likely Shingane as functional engineering of the sword firstly appeared in Nara or early
Heian period. I can understand this statement but I believe it‟s not entirely correct as there were
many different types of complex constructions and to discard the others in favor of the supposedly more common may result in losing interesting options. At this regard it would help a scientific and systematic study of sectioned Jokoto from different periods and excavated from different locations. Sadly, the available material seems to be scarce, likely due to the destructive nature of the needed metallographic examinations. So far I‟ve been able to find only the studies of
Suenaga Masao that sectioned a few Jokoto swords from archeological sites and the studies of
Masakuni Ishii on WarabiteTo and both are accurate but not recent. As this is a delicate and
quiet complicate matter, a better explanation of the terms Kawagane, Shingane and Hagane is
needed :
- Kawagane means “Skin steel - Outer steel”
- Shingane means “Core steel - Inner steel”
- Hagane means
“Edge Steel - Steel which the Ha is made of”
Hagane has a unique meaning that can‟t be misunderstood and is rarely used, but a Japanese
friend whom I rely on, with his usual kindness explained to me (confirming my opinion) that
Shingane and Kawagane
“are not strictly technical or legal terms. Therefore, they do not always have unique concrete
definitions as you might expect. Even among japanese native speakers, there may be different
opinions. The meanings of “Kawagane” and “Shingane” as “skin iron” and “core iron” respectively are general interpretations. Especially, “shingane” is a term used not only for Nihonto. So,
the terms are not automatically connected with the characteristics of the materials used for the
blades. However, when we talk about Nihonto, we tacitly assume that Kawagane is high carbon
quality steel and Shingane is inferior soft steel. This is a tacitly understanding which is valid only
among Nihonto community. That understanding is natural for us, but when you talk about the
unique construction of ancient blades, it might be better to clarify the usage of different materials explicitly to avoid unnecessary confusion”.36 This specification was needed for the sake of
this work as early swords shows types of complex construction that might look strange to nowaday‟s NihonTo collectors but that makes perfect sense in such an early period in which Korean
and Chinese influences were very strong. Kawagane and Shingane, in fact, commonly refer to
the two types of steel we find in Kobuse, the present-day most known and common lamination
method. In the common understanding of this type of construction the Kawagane is higher quality steel with an adequate carbon content and carefully manufactured while the Shingane is a
steel of scarce quality to which isn‟t given a special attention in manufacturing. Not to mention
that this understanding might be not entirely appropriate even for nowadays NihonTo appreciation, I‟ll try to demonstrate that this doesn‟t apply to ancient swords. In fact, as we have seen
with the Jian shown in Fig. 5, in China and consequently in Korea and Japan that the Sanmai
was used also in a “reverse way”, in which the harder steel was placed between two layers of
softer steel. So, in this case, the terms Kawagane and Shingane maintains their meaning only if
we have no preconceptions about the material they are made of. . More, we‟ll see there exists
also “horizontally assembled “ forging methods, in which the soft steel layers are placed over
the harder steel ones.
So here which one is Kawagane and which one is Shingane ? It Is also possible to make blades
by inserting the harder steel into the softer one. This is called Warihatetsu in Japanese. Hereunder Sanmai and Warihatetsu in present-day made Hocho, kitchen knives, that resemble
some of the early types of laminated construction, with the harder steel
placed in between (left) or inserted into (right) two plates of softer one as in
the picture at left.Having in mind that it‟s extremely difficult if not impossible
to judge the type of construction a sword is made of without sectioning it, I
can now beg to disagree with Dr. Honma Junji about the absense of complex construction in such early swords. I think that his statement referres to
a sword with a specific type of construction with four layers (called by Masakuni with the uncommon an quite odd term 四角段刀, Shikakudan-to)
which is supposed to have been produced by hammering a single plate of
steel flat and folding it lengthwise two times, with the edges meeting at the
Mune of the blade. This results in a cross section with 4 layers with no real Kawagane nor Shingane. However it might be there was more than one way to produce a cross section of 4 layers.
Suenaga states that there are complex constructions that result in 2,3,4,5 and 6 layers, assembled either vertically or horizontally. The explanation of folding twice the same steel bar works
for 2 and 4 vertical layers only and even for these there might be other explanations that include
the use of different steels as well. I‟ll try my best to depict all the possible variables starting from
the already mentioned studies and to link them to later more complex constructions in a sort of
genealogical tree. Here Suenaga suggests that 4 layers swords can be made also lining-up 4
different bars of steel :
“it seems that the depicted blade is forged of four vertically lined-up pieces of steel”.37
There is also another possibility that in my opinion could explain better the presence of 4 layers
in the mune. The blade is made hammering flat two lined-up bars of steel of different carbon
content and then a single fold lengthwise is performed. This would avoid having a weld in the
Ha, with possible detrimental effects on the reliability of the blade (see figure B in the table
“Interpretation of early complex constructions). In a similar way, using a single bar hammered
flat and folded only once we can explain a two-layers complex construction that appears in the
Mune of some blades, with no detrimental results on its resistance to shocks (Figure A in the
above mentioned table). Also the Shikakudan type described by Dr. Honma Junji produces four
layers with two folds instead of one but this solution wouldn‟t work for examples in which is
showed an harder Kawagane. For these we need to hammer flat two bars of steel with different
hardness and fold them lengthwise leaving the softer one in the inner part of the fold. Suenaga‟s
suggestion for blades that shows three layers in the Mune and harder Kawagane is, in my opinion, better explaned by the process showed in figure D, again to avoid placing a weld in the Ha.
Of course these are just interpretations and I can‟t support them with first-hand researches on
actual blades. It is more then possible that Suenaga had his reasons to state what he had published and possibly I‟m not aware of important details about the matter. As regards the diffusion
of the different methods Suenaga writes :
“The vast majority of the higher-quality blades show a vertical forging-method. Vertical and horizontal forging methods (i.e. the way the layers are arranged) are in a proportion of about 70 to
30, but no intermediate or compromise forging methods are found. Most specimen consist of
three to five layers, and combinations of two or six layers of steel are rather rare. From this point
of view we can say that in most cases ancient sword blades consist of three layers of steel
forged in a vertical manner, so to speak a shingane with each one layer of Kawagane to the
sides. And the incorporation of horizontally arranged layers too flowed eventually into the wellknown forging methods of the Japanese sword. Therefore it is important for the understanding
of the history of development of the Japanese sword to look back on the forging methods of ancient blades”.38
Entering in better details Suenaga explain the sectioning of Kofun Chokuto in vertically and horizontally assembled method :
” Elaborate blade with a vertically assembled forging method (Hirazukuri Chokuto)
excavated: Kofun near the city of Isezaki, Gunma district, Kôzuke province affiliated with:
Science department of the Imperial University Kyôto
The example shown in picture (6) (plate 41) is divided-up into four cross-sections, shown via
pictures (5) to (9) (see Fig.6). When looking at those cross-sections, one can see that the blade
consists of a Shingane inserted between two layers of Kawagane, and further that the vertical
assembly of these layers is very consistently forged along the entire length of the blade.
Further, there are relative few slag inclusions, which makes this piece – a masterly work – very
carefully forged for an ancient blade. And it can also be grasped that it were such swords which
layed the foundations or set the course towards the later forging methods of the fully developed
Japanese sword. One can see on the basis of each of the cross-section´s synthetical depiction
that the Shingane consists of ferrite, and the Kawagane parts of sorbite. Moreover, these compounds are very fine, and this is the result of a considerable high-temperature forging, namely
the blade had to be exposed to a temperature of about 850°C for a longer period of time. Probably the blade was hardened at a temperaturte
close to 850°C, and was then annealed (yakimodoshi) at about 500°C. A difficult task within
this forging process is to select the proper steel
fragments for each layer. The about 20 mm long
white ghost-line in one of the cross-sections
shows us that there is a difference in carbon
content of about 0,3% to the surrounding layers.
Well, the practical efficiency of a sword depends
on the attention payed to the rough forging, the
forging together of the layers, the heat treatment
and so on, and this blade is from the point of
view of forging technology and skill an excellent
piece”.39
Fig.6
Elaborate blade with a horizontal assembled forging method (Hirazukuri Chokuto)
excavated: Kofun near the city of Fujioka, Gunma district, Kôzuke province
The example shown in picture (11) (plate 42) whose mune is also hardened (still is a single
edged sword) is divided-up into five cross-sections. Pictures (1) to (5) (See Fig.8) show the synthetical depictions. Because at a horizontal assembly of the steel layers it is important to show
the horizontal and vertical course, two cross-sections and synthetical depictions were provided
for each examined section. Well, the corresponding sections between cutting edge and mune
were polished just as much as to get a perpendicular and representative cross-section. Looking
at the cutting-edge area of the synthetical depiction of the kissaki area (1), we see that it conconsists of six layers of horizontally assembled steel layers. What we can assume is that the
uppermost layer consists of a mix of martensite and troostite, layer two contains especially
much martensite, and layer three consists of ferrite mixed with fine-grained martensite.
Between layer three and four, a white ghost-line occurs. Layer four consists of a mix of martensite and ferrite, layer five of martensite, troostite, ferrite, and other structures, and layer six
nearly almost of martensite.
The cross-section for the horizontal layers shows that the mune area of the blade contains
not only martensite, but is actually a mix of martensite, troostite, sorbite, and ferrite. At a closer
inspection of the cross-section, one can see that the martensite content is gradually decreasing
the farther from the cutting edge, and further that the cutting edge itself consists of nearly all
martensite and is therefore able to maintain a certain sharpness. …OMISSIS… In brief words,
the upper and lower regions of the horizontal view of the cross-sections can be identified as
martensite structures. …OMISSIS…The gap in the cross-section (5) is the mekugi-ana
(interestingly here it was sectioned also a part of the nakago). The carbon content is about
evenly distributed over the entire blade. Well, because of the rather low carbon content of this
sword, the cutting-edge and the mune section were treated with yakite, and especially towards
the kissaki, the hardness – and so the sharpness – increases. This we have seen via the high
and increasing martensite structures towards the kissaki area. We should not overlook the fact
that the cutting-edge was contrary to this – so to speak as countermeasure against fragility –
once more treated with a high amount of yaki-modoshi. It was this sense of regulation within the
craft of sword forging which leventually led step by step eventually to the development of the
Japanese sword”.40
There are two interesting things we have to consider when talking about ancient laminated
methods. The first Is that many of the swords in the time we‟re considering were made of imported iron, in the form of small bars often from different original sources, or mixed with indigenous (depending on timeframe) or recycled metal. It can be supposed that some of these
Fig. 7
swords have an uneven distribution of the carbon content due to the different amount of carbon
present in the several bars used to hammer out the starting bar(s) that were combined together.
So the choice of the starting material was, already back then, a very important process, but subject to availability of the rough material. Steel with an homogeneous and correct carbon content
was possibly a problem, and the quantity of impurities too. Identical workout on small bars with
different carbon contents gives the result of zones with different carbon contents in the final bar/
s that will form the finished blade. This is evidenced in the studies of Suenaga, in which uneven
distribution of carbon content, presence of slag even of important dimensions and bad welding
often appears in the sectioned blades. From the above description we see that Suenaga studied also the section of the Nakago with the Mekugiana. I‟ve been lucky enough to have a collaborative friend with the same interest in ancient japanese weaponry that provided me with a
picture of the broken Nakago of a Late Kofun Jokoto in his collection. . It‟s preserved in the Habaki/Fuchi of the original mounting and it possibly gives us much interesting information, or at
least material for suppositions. In my opinion it shows a Sanmai construction, with implications
on the forging process.
In this ancient Nakago we can clearly see different bars welded together. But is seems to tell
more. Notwithstanding it‟s slightly angled it looks like it was built not by three vertically lined up
bars as Suenaga seems to suggests about the one (Fig.6) discussed before, but by two, the
Kawagane one folded wrapping the Shingane, very much like today‟s ones. The thickness of
the three layers looks appropriate and balanced, the shape of the Shingane bar still has a very
regular appearance notwithstanding the centuries and strong oxidization. An uneven distribution
of Shingane is a concern in traditionally forged blades with complex construction and often a
matter of discussion about the effectiveness of some of these methods. It seems to me this isn‟t
the case.
Fig. 08 Laminated late Kofun period chokuto. Looking
into the remnant of the tang preserved into the habakifuchi. At right layers boundaries highlighted, yellow is
outer board of Kawagane, red is outer board of Shingane.
Boris Markhasin collection.
I stated before that there is no absolutely safe
way to tell if an healthy blade has complex construction without sectioning it, but technology
makes available tools that might help us, still
maintaining the needed prudence.
The following is an image of part of the Mune and all the Nakago of a long straight Tachi and that
is dating to ca. 600 AD. Nagasa is 85.5 cm with a 17 cm tsuka, and a 1cm Kasane (Fig 09). A
radiograph has been taken with a commercial technology called Gamma Radiography (Sr 92
source) used to detect structural defects in metals. The result of the radiograph has been adjusted in saturation to obtain the picture hereunder. It possibly shows lamination in several areas
of the Nakago and could suggest 2 differing steel compositions in the blade and into the upper
Nakago. The saturation gaining of the image to attain the supposed differentiation of two metals
has resulted in the loss at the outside border. Consequently, what might be Kawagane has been
reduced in thickness by 30% in all the blade and Nakago length. However, if the suppositions are
right, then the Shingane is thicker in any case. This is possibly explained by the use of the form of
complex construction depicted in fig.10 plate D and by loss of material due to oxidization. Two
Mekugiana are shown and what seem two weak areas as well. It looks like there is a repair with
a differently built bar. The sword is very long and the Nakago is hidden by Tsuka remains, so
mine is a shot in the dark with blinded eyes, but in the course of narrowing, it looks like what
could be the Shingane is lost about 40% along the tang: The rest might be only Kawagane, suggesting this sword was built inserting the Shingane only from half the Nakago onward. This
matches with what suggested by the previous image of the cross section of a tang dated around
to the same period.
Fig. 09 Long straight Tachi , around 600 A.D., Markhasin collection.
The last section which appears thicker and healthier, starting just after the second weak point, looks
like the result of a mending or compositing a new section of metal. There is also a delamination just above
the second Mekugiana what might be an inserted repair point. The sword is still under examination and future results will possibly give more information. It seems that Dr. Honma Junji and Suenaga Masao disagree on how some construction methods were obtained but it might be a matter of interpretation. So I‟ll
now discuss about how the 2, 3, 4 and 5 layers swords might have been constructed. We‟ll refer to the figure 10. Images A B C and D are rendered according to Dr. Honma‟s opinion of a single bar of steel hammered flat and folded lengthwise, either once or twice, while at left there is the literal interpretation of Suenaga‟s “lined-up” construction. We have to consider the construction types under the point of view of reliability. The difference is easily spotted in the most important part of the sword : the edge. Building the
swords with a lined-up construction would mean having the weld/s between bars both in the Mune and in
the Ha. This means that the Ha could be subject to catastrophic failures if the welds are not very well made.
In “one-fold/one bar” and “one-fold/two bars” (Shikakudan) constructions the weld/s occurs in the Mune
only, a part of the blade much less subject to stresses then the edge. Basically, it‟s a safer and more robust way to produce a sword that shows the same number of layers in the cross section. If we apply this
reasoning to the 3 layers
construction too, something
Fig. 10
doesn‟t work. An alternative
way to obtain a 3 layers vertical construction without a
weld in the edge is to use
only 2 bars of steel. The first
one folded to wrap the second. This might be an evolution of the “one-fold/one bar”
construction, but seems such
a construction was already in
use in China in ancient times.
The difference between this
one and the Sanmai is that in
this
one
the
harder
steel ,when present, has to
be placed to form the outer
layers, while in the Sanmai
the hard steel is placed inside. As the blade discussed
by Suenaga shows the
harder steel used as Kawagane, then the “one-fold/two
bars” construction seems the
better solution. The same
would work for a four layers
construction as well. Hammering flat two bars of steel,
welding them one upon the
other and then performing a
single fold lengthwise we
would have a section as in
picture H. For sake of sim-
plicity I‟ll use two templates that resemble the
section of a present-day
Hirazukuri for Jokoto and
Shinogizukuri for NihonTo,
highlighting with different
shades of grey the different steels, the lighter the
grey the harder the steel.
Fig. 11
Now, I would like to quote Honma Junji from NihonTo Koza (in the translation of Mr. H.Watson)
when discussing Ko-Bizen swords made in the very early periods of the fully developed NihonTo (second half of Xth century) :
“Jitetsu: As for the works of this jidai, there are a great many which seem to be close to muku
kitae (also called Maru , made of one kind of steel), and even with those that have been polished down quite a bit, there are very few in which the shingane comes out of the ji and becomes rough.” 41
Dr. Honma Junji previously appreciated the Jokoto in the Shōsōin as without Shingane and possibly made in the “two-folds/one bar” (Shikakudan) construction. His opinion is highly regarded,
with good reasons, and we must consider it very seriously.
So, at least a few KoBizen blades show Shingane. However I can‟t get more precise details
about the over polished swords mentioned. Considering that complex construction either pilingup or welding side-by-side plates of steel was already in wide use by far and that Shingane is a
term used when talking about and in the context of the blade construction but not implying any
type of quality of the material (i.e. in a Honsanmai construction the inner steel is the harder
one) , I can try to give possible explanations for the rarity of KoBizen swords showing rough
Shingane :
-
The KoBizen swords showing no Shingane are skillfully made in the old “one-fold/one
bar” or “two-folds/one bar” (Shikakudan) way, a single bar of steel folded once or twice,
lengthwise. Being the steel the same for every layer it‟s hard to distinguish between layers even if heavily polished. Not so for the ones made in (Hon)Sanmai or Makuri in
which the difference between steels can be more evident.
-
Muku / Maru Kitae has always been used, together with other types of construction, or
was (re?)introduced in long swords smithing too, using only top quality steel, now no
longer imported because availability from indigenous bloomeries, maintaining the production of a smaller amount of swords with Shingane, again with the same high quality
Kawagane. The latter eventually proved to perform better dooming to oblivion the Muku /
Maru construction for long blades in a relatively brief time.
-
All the swords have Shingane but the steel used as Shingane in such early swords is of
a quality as high as the Kawagane. Both steels had an equally accurate Tanren. The
difference is only in the ability of the two steels to react to the hardening process reaching different hardness, e.g. they differ in the carbon content only. This would mean that
no difference in quality (both well-refined) nor in pattern (folded the same way and with
the same care) is discernable. Hence a great difficulty in discerning the two, making the
“becoming rough” (ruining the appreciation of the piece) a rare occurrence.
-
The ones with rough Shingane were the majority but most got discarded and replaced
long ago while the less numerous ones in one-piece construction survived more easily
(under this point of view a sword with complex construction has a shorter life in real prolonged warfare situations). The over polished survivors being the best/most revered
ones or simply the ones that got over polished late enough.
-
The Shingane in (some of?) the healthy ones is thin and not revealed yet.
-
A combination of some or all of the above.
Now let‟s discuss the hada and the activities due to the use of differential hardening in early
swords compared to later ones. We‟ve already seen how the technique of folding the steel during the smithing has reached the archipelago with Korean immigrants and that it was in use in
China for centuries. Now we should look at similarities in the ancient works and the workmanship found in later, fully developed NihonTo. To do this, we‟ve to use the better preserved ancient swords available, as to say the ones treasured in the Shōsō-in Depository.
Dr. Honma Junji describes them this way :
“Kiri-ha-zukuri are the most popular type and there are swords in shinogi-zukuri that look like kiri
-ha-zukuri at a glance, also many kissaki-moro-ha-zukuri (mostly kiri-ha-zukuri) are seen
amongst them. There are also some swords in Kogarasu-zukuri. Shallow sori is recognized in
them, their mi-haba is wider than that of the Japanese sword in general, most swords have
maru-mune, jigane looks soft, nagare-hada is common and masame-hada is also seen, and
hoso-sugu-ha is popular and skillfully tempered. Boshi is sugu or gentle then turns back in komaru with short kaeri and is elegantly tempered with tight a nioi-guchi. The jigane is covered
with thick ji-nie, sunagashi and hakikake are seen, and the hamon starts with yaki-otoshi.42
“Kiri-ha-zukuri are the most popular type and there are swords in shinogi-zukuri that look like
kiri-ha-zukuri at a glance, also many kissaki-moro-ha-zukuri (mostly kiri-ha-zukuri) are seen
amongst them. There are also some swords in Kogarasu-zukuri. Shallow sori is recognised in
them, their mi-haba is wider than that of the Japanese sword in general, most swords have
maru-mune, jigane looks soft, nagare-hada is common and masame-hada is also seen, and
hoso-sugu-ha is popular and skilfully tempered. Boshi is sugu or gentle then turns back in komaru with short kaeri and is elegantly tempered with tight a nioi-guchi. The jigane is covered
with thick ji-nie, sunagashi and hakikake are seen, and the hamon starts with yaki-otoshi.43
Japanese sword researchers have agreed that there is a connection between the workmanship
of the swords preserved in the Shōsō-in Depository and the Japanese swords that were developed during the Heian Period in the Yamato tradition. Senjuin, Tegai, Taima, Hosho and Shikkake schools shows common features in their workmanship, and all related to the Ji and Ha of
the swords of the Shōsō-in, making the schools in Yamato tradition rightly descended from the
swords in the Depository. 44 However there are also differences. On this subject Dr. Honma
states:
Now, I would like to point out differences of the workmanship between old Yamato swords and
the swords of the Shōsō-in Depository. (1) Tachi by Yamato smiths are in shinogi-zukuri and
have sori. (2) Their jigane look powerful and nie is more emphasised in the ji and ha, sunagashi
and hakikake are more conspicuous. (3) There is no tsuchi-me and sen-suki finishes on their
nakago but taka-no-ha, higaki, kiri-yasuri. It must be noticed that the width of their shinogi-ji is
wider than that of smiths who lived in other provinces and were active in the same period.…
OMISSIS… After researching the swords of the Shōsō-in Depository, it becomes clear that the
workmanship of the swords in the Shōsō-in Depository had an influence on the sword forging of
Yamato smiths.” 45
So with a technical point of view there is a certain continuity between Jokoto and Yamato tradition, even if I‟m still struggling with the differences in activities that Dr. Honma highlighted hereabove. The reason for such differences might lie in the steels used, as seems the one which
the swords of the Shōsō-in are made of is softer than the one used later, but also of very high
quality and extremely elastic, as attested to by Mr.Ono Kōkei, polisher of the blades in the
Shōsō-in, who states this steel calls to mind the ones of the Naminohira School. Dr. Honma
Junji, Mr. Miyahiri Shōhei and Mr.Takahashi Sadatsugu are strongly convinced that the blades
in the Shōsō-in were made with the Tanren (folding and hammering) method, using a very
strong and elastic steel that we can‟t replicate except in the carbon content. Mr. Miyahiri believes the steel was heated in a reducing atmosphere at low temperature with a top quality charcoal fire. Such a process was repeated about ten times for the long blades. Mr. Takahashi considers these blades the result of remarkable skill even surpassing that of the Kamakura Period.46 And Mr Miyahiri reported :
“It is wrong to state that Kamakura Period was the peak of Japanese swords. The uncontrived
lively effect of ji-nie is almost unbelievable”.47
We can infer by this that Mr. Miyahiri was convinced of the japanese origin of the blades. The
above discussion has led us to wonder about the differential hardening process.
Clay coating
A very debated matter regards the use of a clay-coating process, the “Tsuchi-tori”, to produce
two areas of different hardness. Differential hardening was already in use by far in China. A
steel single edged broad sword and double-edged steel swords unearthed from the tomb of Emperor Liu Sheng (d.113 B.C.) at Mancheng (Hebei) gives evidences that the technique of differential hardening was already in use at this time.48 The metallographic examination of the cross
section on one of these swords shows a quench-hardened martensitic structure only in the cutting edge that, even if heavily corroded, still shows an hardness of 900 kg/mm 2 , while the
spine is only pearlite with a small amount of ferrite. 49 Notwithstanding this it‟s still debated
whether the use of clay-coated differential hardening in Japan was within the timeframe we‟re
discussing. Present-day smiths proved to be able to achieve a Yakiba with different hardness
then the rest of the blade even without Tsuchitori and it has been suggested that the emergence of Choji pattern has its roots in this “clay-free” process in a way that reminds the uzumiyaki for warabiteto described later. However the Chinese swords and the Japanese ones made
following their models show astonishingly well defined Suguha Hamon and well-defined Boshi.
The presence of Yakiotoshi is another puzzling detail. Such precision is hard to explain without
an insulating material for fixing the borders of the Yakiba in such a precise way. It has been
suggested that the original continental technology used oil as insulating material to produce
these early swords. It is supposed the process was not different from the one we‟re familiar
with; the blade was coated with oil, then a thin strip of oil was wiped off of the edge of the sword
and the blade was heated and quenched to obtain the hamon. Clay coating began to be used in
the mid-Kamakura and that only at the end of Kamakura period all the blades were subject to
the present-day well known process of hardening through clay-coating. In my opinion this theory doesn‟t work, for a simple law of physics. Natural liquids evaporate at too low of a temperature to sustain the Yakiire process. Following the oil theory, Japanese eventually would hava
had to use vegetal oil, lacking the present-day chemical industry. I don‟t know which type of
vegetal oil it is suggested to be used, but I know that the vegetal oil with the highest evaporation
point I‟m aware of is Safflower (Carthamus tinctorius ) oil that has its boiling point at 510° F
(266° C) while refined Soybean oil evaporates at 495° F (257° C). I‟m not aware of the boiling
temperatures of animal oils such as the ones produced by whales, so to be safe I‟ll add the extreme liquid material in nature, mercury, that is a metal and evaporates at 674° F (356 °C). All
temperatures considered at the standard atmospheric pressure of 1 bar (meaning the sealevel). Any liquid I‟m aware of would evaporate in the heating process of Yakiire, that reaches
much higher temperatures, between 1,341° F and 1,470° F (around 727° to 800° C) or more. 50
Even considering the statement that the blades of the Shōsō-in were hardened at low temperatures, there is a limit that you can‟t pass if you want obtain Martensite, as it doesn‟t occur below
1,341° F (727 °C). Even considering that the Japanese had a strong enough oil, this solution
would still give us some problems with the precision showed by Suguha, Boshi and Yakiotoshi
of the blades in the Depository. Oil is far from being as good as clay to insulate from heat, can‟t
be placed in as a thick layer as clay and consequently it couldn‟t be applied in a thick enough
layer to obtain the same results we can see in the Shōsō-in blades. More, in my opinion it
wouldn‟t remain firmly in the desired/required position when the blade is heated in the furnace
because it is prone to the physics of a liquid material. Just simple gravity might be enough to
move it down and cover the narrow edge, or if we consider placing the blade edge up into the
furnace, it would move down exposing more metal. If the blade touches the hot charcoal it
would ruin the shape of the hardened edge because friction with charcoal would remove the insulating coat of oil. To not ruin the insulating coat is a concern even nowadays in the smithing
process using clay.51 Such an unfortunate event is registered by Suenaga in discussing the
metallurgy of sectioned Jokoto, badly rusted, from the Kofun period he studied. He gives renditions, based on photos optically magnified at the best technology available back then. Metallographic investigations were effected at the same time.
He writes discussing the sections of a sword in vertically assembled forging method :
“It seems that the depicted blade is forged of four pieces of vertically lined-up steel. Picture (4)
shows the depiction of the cross-section shown in picture ②, and we can see the deeply hardened edge section. Also along the core, the sides, the area close to the mune, and the mune
itself, we can see a martensite structure, and therefore the sharpness of the blade can be imagined. However, the white ghost line (i.e. the white line close to the right side) indicates a weak
section of the blade. Anyway, this occurred probably due to an insufficient heat-treatment during
the forging (that means the steel was too cold)”.52 (Fig. 12A) and again about 2 different swords
with horizontally assembled forging method: “Picture (2) shows the depiction of the crosssection shown in picture ②. The cutting edge consists of martensite, and one region of the core
section consists of so-called „troostite“, namely a structure which contains small punctual islands of martensite which is caused by hardening. And we can see that one side and an area
close to the mune consists of troostite too. It is conceivable that this was the result of clay sections peeling off during the heat-treatment.”.53 (Fig.12B) ...omissis...“Picture (4) shows the depiction of the cross-section shown in picture ② from the central picture sequence. Somewhat
away from the very edge of the sword, a martensite structure is visible, …, it seems that this
area was not sufficiently covered before the yakite treatment and got therefore too
hard.” (Fig.12C) It‟s clear from the above statements that Suenaga considers the use of claycoating as a matter of fact and never even try to find an alternative explanation. For the mentioned reasons I don‟t consider the oil option a viable one to produce blades with the refined details such as the ones in the Shōsō-in. This, of course, doesn‟t exclude that certain types of
Hamon can be achieved also without clay coating as high-ranking smiths experiment with nowadays , and that this might have been an alternative technology in the early periods. However in
my opinion it‟s neither a probable scenario for most of the Hamon designs nor for good quality
swords such as the ones in the
Fig. 12
Repository. In the end, about
the use of clay in the differential
hardening process I tend to
agree with Honma Junji´s opinion, who writes :
"...It admits no doubt that the
swords preserved in the Shōsōin, like those of later periods,
were fashioned by heating, folding and hammering repeatedly,
and were tempered (hardened)
with the Ji (“ground”, unhardened part) covered with fire clay
(tsuchi-tori, clay coating) …
OMISSIS… Furthermore, the
clearly defined regular hamon
which are to be regarded as the
prototype of suguha, and the
wavy terminating in everted komaru form recalling the style of Nagamitsu of a later period are absolutely impossible without
the tsuchitori process. Concerning these respects the author (Mr. Honma) once asked the opinions of the late Mr. Takahashi Sadatsugu and Mr. Miyairi Shōhei, both registered as Important
Intangible Cultural Properties (Living national treasures) in the field of swordmaking, showing
them a few examples while Shōsō-in blades were being polished. Both were strongly in support
of the view that the blades had been made in the Tanren (folding and hammering) and tsuchitori (clay-coating) methods".48 I tend to exclude the blades in the Shōsō-in were quenched, with
or without Tsuchitori, into oil for the presence, amount and quality of activities.
The Japanese sword in VIIIth, IXth and Xth century C.E.
Wars in the North East and the Warabiteto
The importance of eastern Honshu as source of horses and skilled horseriding archers can be
seen also in the revolt of Fujiwara no Hirotsugu, exiled by the Court to Dazaifu after his family
lost the control of political key positions due to the extermination caused by the great epidemic
of smallpox in 735. The Court had access to the Kanto in order to add skilled soldiers to increase the number of mounted archers in its army. Hirotsugu, being limited by his position in the
southern island of Kyushu, wasn‟t. Again, the importance of controlling the Kanto was a key to
victory for the court.55 We‟ve already seen in the first part of this work that the Kanto was already shown to have had a relative autonomy from the Yamato Court, but it served as a vassal
and was important for the military as a source of horses and mounted archers. Before entering
a specific lecture on how the wars in the East affected the development of the Japanese sword
it‟s better to know how the nature of the opponents, the “Emishi”, affected their fighting. We
know they were culturally different by Yamato, but archeological evidence tells us that they possessed wet and dry agriculture, metalworking and that they they followed the practice of burying
ranked people in large earthen tombs. The Kanto at this time resemble a snapshot of Western
Honshu in the 6th century, possibly even in the habit of trade warriors and horses to obtain iron
and goods, as happened to the west during its relationship with Korean reigns. They considered
themselves politically independent from the Court. On the other side the Court felt the duty to
bring civilization there and surely the fertile lands and wealth of the region played a role too in
the Yamato politic.56 It can be suggested that the first contacts and attempts of civilization weren‟t necessarily warlike. Local strongmen (Kuni no Miyatsuko) from the Eastern Provinces such
as the Kenu and the Abe families claimed to have a certain control on them and Yamato Court
held them responsible for the law and order in the region. 57 Abe no Omi Hirafu during his expeditions founded several district headquarters and palisades at Nutari and Iwafuni, along the Japan sea. In 708 A.D. the government set up the Dewa Office for the conquest of the Northern
Barbarians, at north of Iwafune, supplying it with weapons and armor. This, together with the
building of many palisades, Districts and Provinces tell us that the Region had reached an high
level of strategic importance in the eyes of the Court.58 However these administrative outposts
shouldn‟t be equated to firm Yamato control over the region. Possibly irritated by the increasing
presence of the newcomers and by the military buildings, the Emishi revolted in 709 and 720
and 724.59 A great revolt was quelled by Ono no Azumabito using 1000 mounted soldiers from 6
different Kanto provinces.60 Relative peace prevailed until 774 but the colonization policy and
military reinforcement of the region, such as the building of Fort Taga and Fort Akita in 737, Fort
Okachi in 759 and Fort Iji in 767, provoked violent actions by the Emishi. 61 Forts could have
been elaborate to the point of including temples, office buildings, storehouses and two different
levels of walls. This might mean that the functions of these forts were both political and military.
The “Wars in the Northeast” period began in 774 when residents near Fort Monofu in Mutsu
Province revolted.62 A total of 5 expeditions, namely in the years 776,788,794,801 and 811,
were conducted by the Court in Mutsu and Dewa. Causes for outbreak of hostilities have been
found on both sides, but the desire of the Court to display its power and greed for land and resources are likely the most important, although the need to drive attention away from unwise
fiscal policies by the Court 63 and/or the struggle between native chieftains and Court Officials
must be accounted for 64 as when a trusted lieutenant like Iji no Kimi Azamaro, magistrate of Joji
district and of Emishi stock revolted against the construction of Fort Kakubetsu just north of Fort
Iji.
His revolt led to the pillage of buildings of Fort Taga. The wars were extremely harsh, prostrating regions and driving resources from the Bando. For a period the Emishi were able to defeat
the Yamato‟armies with a “strike and flee”, guerrilla tactics, well fit to the environment and the
organization of their forces. We find interesting accounts about these battles in ancient accounts :
…the barbarians’ custom is battle as mounted archers. Ten of our commoners can not rival one
of the enemy. 65
They swarm like bees and gather like ants… But when we attack they flee into the mountains
and forests. When we let them go, they assault our fortifications… Each of their leaders is as
good as 1.000 men. 66
By 500, in fact, horse trappings and other evidences of horse riding, like Haniwa of horses with
saddle and stirrups, became more and more common in the Kanto and Eastern Honshu 67 and
Japan‟s leading experts on tombs believe that, by the 500s mounted warfare was probably most
popular in eastern and northern Honshu.68 and it seems reasonable to think the Emishi established fighting tactics the Yamato soldiers weren‟t familiar with. This and the perfect familiarity
with the terrain made them feared opponents. The Kanto, of Emishi breed, already proved to be
a valuable source of brave soldiers and the Court arrived at the same conclusions as did US
Army, many centuries later : “you need an Apache to fight an Apache”. But the Emishi had their
own Geronimo. In 784 Emperor Kammu appointed Otomo no Yakamochi to lead another expedition, after previous unfruitful attempts. He also ordered that the provinces of the Kanto should
establish forces composed of military specialists. This edict was issued during the lowest point
of the confrontation between Yamato and Emishi and is a strong indicator of the growing reliance of the Court in military experts from the Kanto. The preparations for war continued until
788 when a supposed army of 52.800 foot soldiers , horsemen and porters gathered at Fort
Taga under the command of the Great General to Campaign in the East, that received the
warning from Emperor Kammu : “The safety of the Nation resides in this one expedition”. 69
From Fort Taga in the spring of 789 the army entered hostile territory, divided into three groups.
2.000 men crossed the Koromo river, searching for “the chief bandit Aterui”, that is remembered
as the most legendary fighter among the Emishi. After having burned down Sufushi, Aterui‟s
hamlet, the Yamato Army was faced by a strong Emishi force. When retreating, they were
trapped in the middle of the river by another Emishi contingent coming from the rear. The errors
of Yamato‟s Generals from Honshu lead to the loss of 5 generals and a total of 1061 soldiers.
No accounts about the number of porters. A great loss of military material occurred as well, material that went to strengthen the Emishi forces.The defeat at the battle of the Koromo river
would take its place among Japan‟s military disasters, bitterly remembered as a defeat at the
hands of a barbarian people and assured that Taibo no Kimi Aterui had a place in history. The
Court immediately began to prepare for another expedition. In 791 Emperor Kammu asked for
military help from the Kanto once again, and appointed Sakanoue no Tamuramaro among the
leaders of the army. In 792, 793 and 794 various hamlets in Tohoku surrendered to the
“100.000 men army” (figure surely exaggerated). Now the Court was able to reinitiate their colonization efforts. Tamuramaro was able to win because he was able to maintain a unique and
total command of his forces and was rewarded with the title of “Sei I Tai Shogun”, The Great
General Who Quells The Barbarians. In 801 Tamuramaro pacified the last territories still giving
troubles. . Aterui surrendered in order to stop the killing of his people and was executed ,18
September 802, in Sugiyama, notwithstanding Tamuramaro‟s requests to the Court to save him
and let him help to rule the conquered lands.70 The Court had to stop the military conquest of
Tohoku because their finances were exhausted. The frontier was quiet until 811, when Fumiya
no Watamaro, a pupil of Tamuramaro who had succeeded in the title of Sei I Tai Shogun, lead
troops from Mutsu and Dewa together with submitted Emishi (Ifu, Fushu) to the final conquest of
the last part of Honshu, after 38 years of warfare. In this period we still find the types of swords
we‟ve already discussed before, but the turning point of the development of Japanese swords
into what we are now used to refering to as NihonTo is the appearance of WarabiteTo. The oldest example I‟m aware of has been found in a tomb in Ibaraki, Kanto, and dates to late VII th century 71 even if the use of swords by the Emishi is documented as fas as the IVth century. 72
This seems to match with the theory that Kanto acquired with time a certain technological independence from the Kinai. According to documents of the late VIII th century period, at the apex of
the Wars in the Northeast, the Provincial Headquarters manufactured swords, bows, arrows and
armor. A good documented example of the way the wars affected the nature of the weapons
used is surely found in the modification of the Armor from iron to leather. 73 This enabled the Yamato soldiers to ride in a light and agile way, the same as their opponents following the
“Counter Response and Symmetry” strategy. All changes in weapons design and materials had
to be approved by the Court, and examples had to be sent for approval. 74 Even if I‟ve not been
able to find written evidence, this lets me speculate that local designs could have been sent for
approval to the Court and taken as examples in production of swords by Yamato smiths, either
from the Kanto or the Tohoku, The design of curved Warabiteto, used by Tohoku natives and by
Kanto soldiers, could have been adopted by the smiths operating for the Yamato Court in the
Provincial Headquarters but not only that. The system of Court approval could have been the
door though which the curvature in the tang (and successively/consequently in the blade) entered the western regions, to be applied to KarayoTachi. Reading “The Ordinances of Engi”,
thought to reflect the situation of the IXth century, the diffusion of the idea of curvature could
have been helped also by the forced relocation of thousands of Emishi from subjugated regions
in almost all the rest of Japan, with the dual target of breaking their resistance in the native
lands and as police for peacekeeping against peasants revolts, even if they themselves revolted wherever located, revolts often quelled by soldiers of their own breed, such as the big
one that occurred in Dewa in 878.
We‟ve already seen that Kanto had a special position in the Court‟s politic due to its military importance. The Kanto was strong enough to force the Court to gain its support avoiding the direct
military option, using a “Divide et Impera” politic. However how could this region have been so
strong under a military aspect ? We know the plain was used for horse breeding, and horses
were valuable goods to trade for iron, but the key is the capacity to smelt and work iron for
weapons production. Later we‟ll see that Warabiteto shows interesting elements of smithing
technology that have
Map 2
to be attributed to a
quiet evolved smithing
technology, as complex construction and
differential hardening
through clay coating,
technologies already
achieved by far in the
west but that still look
uncertain in the Kanto
and Tohoku areas,
confirming the gap of
a couple hundred centuries we already suggested between Kinai
and Kanto / Tohoku,
as is to be expected in
border regions. Here
however some differences seem to have occured and a short explanation on ironworking is required. Ironworking was firstly achieved in the Mediterranean area and Middle East. It consisted
of smelting ore in small furnaces called bloomeries and then forming the products through
smithing on an anvil. This method was simple and required a small amount of labor It was diffused into the Central Asian Steppe where the nomadic Scythian‟s carried the technology into
Eastern Siberia by the VIIIth century b.C.
The Chinese invented ferrous techniques on their own, possibly as early as 900 B.C but not
reaching proficiency in producing blades and tools from iron ore before the VI th century b.C. 75
Chinese method involved a much bigger amount of work and huge blast furnaces with more sophisticated heating technology allowing greater efficiency and production. By the Vth century
B.C. both technologies were available in Korea, but the spreading routes into and down the
country have not been found yet. Later evidence suggest Korean‟s adopted the Scythian
method, but some questions are still to be answered hence we can‟t totally exclude a Chinese
influence (blue route in fig.13). The evidence of tools for smithing suggest the Japanese followed the Korean‟s model of the Scythian tradition of ironworking instead of the Chinese one, 76
as later Japanese furnaces resemble a variant of a bloomery. The later appearance of an
“Eastern type” of furnace might have been either a local achievement or influenced by trade
with Manchuria through the supposed “Northern Route”. In fact, citations in Nihon Shoki and
Shoku Nihongi indicate that the Emishi maintained direct contact with peoples across the Sea of
Japan. One such group was the seafaring Mishihase, with whom the Emishi to the north of Koshi, along the Sea of Japan coast, exchanged goods at designated beach sites. In 713 Parhae
(also known as Bokkai or Balhae), a Korean-Malgal kingdom, was established in Manchuria and
began to seek relations with the Japanese state at Nara. Diplomatic missions from Parhae visited Japan throughout the eighth century. Most landings were at Dazaifu, a military installation
and port on the northern coast of Kyushu, but a significant number also came ashore in Dewa
and from there made their way to Nara. According to the Shoku Nihongi, some missions were
forcibly detained in Dewa by the Emishi. However, as Nakamura Shuya suggests, Parhae diplomats probably had an interest in developing political and economic ties with the Emishi and may
have voluntarily remained among them. The sea and land routes that gave access to the continent from northern Honshu and Hokkaido are not known. However, a "northern route" and
"Parhae route" are mentioned in Shoku Nihongi and suggest that travel through the northern
Sea of Japan was common. Morita Tei has speculated that the eighth-century Emishi, especially those living along the northern Honshu coast, were sea traders with an extensive network
of domestic and continental partners.77 By the Kofun period furnaces have been found in various shapes including circular, elliptical, square and rectangular. Hashiguchi Tatsuya reproduces
diagrams of two iron-production sites in Kyushu. One of these, excavated in Fukuoka , is fascinating, for it appears to show a type of bloomery which might be an early ancestor of the Tatara
furnace. . It is dated to a time between the late Kofun and the Nara period. 78 It shows that
bloomeries were in use in early times in the Korea-Japan area, and Donald B. Wagner believes
that the bloomery iron-production
technology was learned from Siberia (Scythian method) rather than
from China and as the way which
the iron-smelting entered Korea
have not been found (yet) and that
Chinese themselves might have
been influenced by the Scythian
process as well before their development of iron casting79, the supposition makes sense to me too.
The peculiar construction of this
Fig.13 Supposed dissemination routes of iron-manufacturing
early Tatara may have been develtechnology in Japan.
oped in Korea or Japan in response to the technical problems
caused by the use of iron sand ore.
By the ancient period (8th- 9th century C.E.) the standard become the rectangular chamber furnace but we have also to note that from the early 8th century C.E. in the “Eastern provinces”
there appeared the type with a half-buried, cylindrical vertically oriented furnace with a diameter
of one meter and a width of 1-1.5 meters which is a nice example that has been unearthed in
Fukushima prefecture (see fig.14). This style spread westward to Kinai, reaching the coast of
the inland sea in the 9th century and reached Kyushu in the 10th century. These type of furnaces
became the specific type of the Kanto and “Eastern Provinces” and was effective enough to
give self-sufficiency in iron production for these regions, for the period preceding medieval
times, when these furnaces disappeared.80 These furnaces suggest that the roots of iron manufacturing in the two areas might have been different and is a puzzling addition to the WarabiteTo, which was another feature specific to the Eastern Provinces that appeared around the same
timeframe. In fact the late 7th , whole 8th and most of the 9th centuries C.E. were characterized
by the emergence and spread, in the Kanto and Tohoku areas first and western regions later, of
a type of sword entirely of Japanese design and, so far, never found on the continent that is
named “WarabiteTo” because of the design of its
hilt based on curling
bracken shoots. According
to the places of excavation and goods found together with these swords
their history was concentrated mainly in 8th and 9th
century. Many were unearthed together with Wadô coins, showing they
were made after the Wadô
Fig.14 Remains of an VIIIth century steel furnace in Fukushima Prefecture.
period, 708-715, and the
accompanying grave goods of many were chokutô with kamasu-kissaki and Sue ware, that are
indicators of the Nara period. These swords although relatively short, show a strong curvature.
Masakuni studied more then one hundred specimens showing sori and about 22 show a sori
more than 0,5 cm, and ten of them even a curvature between one and two centimeters. Especially the tsuka has a remarkable sori, and on 52 from the hundred aforementioned pieces, this
part of the sword curves more than one centimeter, and 17 of them show a curve of this part of
two to three centimeters. When looking at the sori of these warabite-tô, the curvature is emphasized along the tsuka, and this tsuka-sori concerns especially early warabite-tô. Warabite-tô were intended as a cutting/slashing weapon, and this is clearly seen along the tsuka-sori, the wide
haba of the blade around the monouchi area, and the stepped kamasu-kissaki. Also the sori of
the blade increases the overall curve of the weapon, which results in a better cutting ability. The
smiths who forged warabite-tô applied therefore consciously a sori, and the emphasis of the latter led gradually to the emergence of a tachi-sugata, and therefore the warabite-tô has to be
regaded in the wider sense as the first step to this development. There are no warabite-tô
whose blade length exceed those of a tachi with 2 shaku, their longest specimen measures just
56 cm in the nagasa but they show over the years a gradual increase in length, and this can
clearly be reconstructed by relics and grave goods.81 The accompanying Wadô coins found together with warabite-tô at Kumadô and Niirone indicate also that the boom of Form I swords
and the emergence of a sori has to be dated to the latter end of the Nara period. Further, warabite-tô from Mirumae , Kashizaki and similar examples, which show an overall sori of nearly one
centimeter, date from about the transitional period into the Heian era, and this corresponds with
the subjugations of general Sakanoue Tamuramaro (758-811 C.E.).
Subsequent swords which show a tachi-sugata were found at Kanukida, Kumano-sha, Naganuma Long warabite-tô and kenukigata-gatana in tachi-manner and a sori of up to three centimeters were found in Hokkaidô´s Ebetsubuto (nagasa 50 cm), Akita´s and other sites, and the study paper of the historic ruins at Gojôme places them into the Gangyô period (877-885 C.E.), a
dating which is quite appropriate. When we associate the warabite-tô with the subjugations of
the emishi – finding their end with Fujiwara no Yasunori (825-895 C.E.) – we can assume a flourishing period of about 200 years. That means they were mostly in use from the beginning of the
eighth, to the end of the ninth, but probably didn„t last into the tenth century AD. All warabite-tô
excavated on Hokkaidô like the one excavated in Abashiri, Tokoro as well as the Fujiwara Bowl
grave goods found in Sapporo, point toward the early Heian period as the latest limit, and that
the swords found among the relics of Eniwa and Usakumai as well as grave goods and emishi
swords which date into the Kamakura period must be regarded as rare exceptions. 82 Dr. Kida
Sadakichi (1871-1931) was of the opinion that warabite-tô were of Emishi origin, and that the
swords which were
Fig.15
excavated
westwards in the
Kantô area were actually brought down
by those emishi
which were already
captured, or to put it
into other words, integrated into the
then Imperial system. Kida refers to
such swords as
„fushû no tachi“ (lit.
„captured swords“).
Dr. Kida suggests
that from the warabite-tô of the Shôsô´in
and efu no tachi preserved elsewhere (衛府太刀), that kenukigata-tachi were actually warabitetô remodelled to fit the tastes of the Yamato people of central Japan. Further, the term „fushû no
tachi“ (俘囚剣) was also pronounced as „efu no tachi“, but in this meaning it was applied to the
swords of the warrior class in contrast to the actual term „efu no tachi“ (衛府太刀) which described the swords of courtiers and imperial guards. When we look at the research reports of Kodama Sakzaemon (1895-1970), Kôno Hiromichi, Takakura Shin´ichirô (1902-1990), Yonemura
Kioe, Sugiyama Sueo, Itô Nobuo, Gotô Shu´ichi, Sonehara Takeyasu or the more recent paper
of Ôba Toshio, it is still unclear if the origins of warabite-tô were from the continent or in
Honshû. However the accompanying grave goods like magate-gatana or magate-tôsu (early
curved blades) suggest on the basis of analogous items that they belong to the peculiar socalled „Okhotsk culture area“83 although, it is not clear nor proved if and how warabite-tô took
the same course. Such magate-tôsu though were also excavated in kofun´s at Akayu
(Yamagata Prefecture) and Ezuriko (Iwate Prefecture). Further, when looking at the two warabite-tô excavated in Akayu´s Tanukizawa-kofun their interpretation is completely identical with the
warabite-tô found in Moroyo, Hokkaidô, therefore it can be safely assumed that these swords
made their way from northern Japan towards southern regions.
There are currently hardly any eligible reference pieces from the mainland available which
could shed light on the prototypes or the origins of warabite-tô, but a very good indicator is a
large tôsu (ô-tosu) excavated in Kodama in northern Saitama Prefecture . This ô-tôsu (Pic. 16)
– excavated with haniwa figures of young men as grave goods – has a long triangular shape
which is identical with warabite-tô found in these areas. There were also several ô-to (lit. „side
swords“) in tomotetsu-zuka (Blade and hilt as a unity formed from the same piece of iron) excavated from the Takazuka-kofun of Gunma Prefecture´s Tomioka region, which have also the
same shape as this ô-tôsu. So it is possible, but yet to be proved, that such large tôsu were the
prototypes of warabite-tô. Dr. Suenaga Masao´s assumption that warabite-tô were in use from
the Nara to the early Heian period matches with the already suggested timeframe. Suenaga
further suggests that their usage was restricted to a certain region confirming that warabite-tô
were hardly used in the western regions. However, it is a common theory that the fact for the
large number of warabite-tô found in the Tôhoku area and on Hokkaidô has something to do
with the delayed arrived of the kofun culture to these areas. We still have only the warabite-tô
themselves as a starting point for assumptions for their distribution. On the other hand, there is
also the possibility that their usage was restricted to a particular ethnic group or class. Dr. Ôba
Iwao published a comprehensive study on all warabite-tô excavated in Japan at that time.84 The
places these 45 fragments and 56 swords described in this study were foundwas mainly along
the Tôzandô and Hokkaidô routes. This suggests that such swords were worn by the troops
dispatched during the subjugation of the northern tribes. Especially the gradual improvement
northwards, i.e. from the old-fashioned swords found in the Jôshin area (the provinces of Shinano and Echigo) to
the newer models
found through-out
the northern Ôshû
Fig 16
region up to Hokkaidô,
supports
85
this assumption. This theory agrees with the provisional dating of warabite-tô too. Today, we
are able to look at 135 extant swords, and when we now re-consider Dr. Ôba´s theories, we find
out that most of the old-fashioned swords are found in the Jôshin area – especially in Fukushima Prefecture – and that they improve from Miyagi Prefecture northwards. Also when we take
into consideration the tachi-like warabite-tô and kenukigata-gatana excavated in northernmost
Honshû and on Hokkaidô, we can agree with Dr. Ôba´s theory. A different approach has to be
taken with the warabite-tô discovered first and foremost in Iwate Prefecture and westwards to
the Kantô area. According to Dr. Kida´s opinion, it is likely that these swords were worn by persons formerly engaged in the subjugations of the nothern tribes and eventually returned to the
Chûbu region. At the beginning of this process, the swords were brought southwards together
with the emishi warriors, but maybe later southern swordsmiths received the forging methods
from their captured northern “colleagues“. However, among the warabite-tô found in the Tôhoku
area, there are a few specimens which are completely identical with the swords discovered in
the Jôshin area. This suggests that there was a certain intercourse between the soldiers that
participated in the subjugation of the northern tribes and the people who lived in the Kantô and
Chûbu regions.
So when we assume that the form of these swords is the precursor of the Tôhoku sword
form, we have to regard the Kantô and Chûbu regions as the origin of warabite-tô. We already
stated that the production time of warabite-tô can be assumed to be from the Nara to the early
Heian period. When we now take into consideration the delay with which technologies and culture reached the northern Ôshû region along the Hokkaidô route, we can assume that warabitetô were maybe produced there until the latest Heian period, a time, when already Kenukigatagatana, ryûko-zuka swords, as well as kenukigata-tachi were already in use. 86
One problem in these considerations is that the warabite-tô preserved in the Shôsô´in, with its
kissaki-moroha kiriba-zukuri, show a quite peculiar blade form. This blade form – also seen in a
similar way on other chokutô from the Shôsô´in – is namely identical with kara-yô-tachi which
were in fashion in central Japan during the Nara period. When we look at the warabite-tô found
in Tokushima and Shimane Prefecture we can see that a kissaki-moroha tsukuri-komi was the
strong point of central Japan swordsmiths. 87
Masakuni Ishii, in his book “WarabiteTo”, classifies them as follows (pictures from the same
source) :
Form I: Generally in hira-zukuri, with kaku-mune, long nagasa, and sori along the hilt and often
also along the blade. Most tips tend to a kamasu-kissaki. Wide mihaba, neither ha-machi nor
mune-machi, tsuba is mounted from the tip and is held in place by the funbari of the base. According to the places where they
were found, they had prevailed
in the Tohoku area and on Hokkaido, but some examples were
also found in the Kanto and
Chubu areas. About 80% of all warabite-to are of this form.
Form II: Nearly all in hira-zukuri, with kaku-mune, short nagasa, no sori on the blade, or
uchizori. The sugata looks like an elongated triangle. This sugata is also called "willow shape"
and is similar to hocho knives.
The tsuba is mounted from the
tip and there are no machi.
At those swords where the
tsuba is mounted from the tsuka
side have regular notches cut in right-angles at the ha-machi and mune-machi. These were discovered in the Kanto area, in the Chubu area down to the southern part of Fukushima Prefecture. Further three pieces were found in the Tohoku area. About 14,4 % of all warabite-to are of
this form.
Form III: Kissaki-moroha-zukuri, classified into hira-zukuri and kiriha-zukuri , generally with a
maru-mune. Hira-zukuri blades
are short, and both hilt and
blade have no sori while Kirihazukuri blades are medium sized
or long and narrow and show
quite a strong sori along the hilt. There are ha-machi and mune-machi and the tsuba is mounted
from the tsuka side. Pieces were discovered in the Kinai area (preserved in the Shoso´in,), on
Kyushu, in the Chugoku area, in the Chubu area, and in the Kanto area. That makes altogether
4,5 % of all warabite-to.
Although they should be regarded as an exception, there were two Form I swords discovered
in Tôkyô, and one Form I sword in Nagano. Dr. Kida judged these swords as indicating the transfer by the aforementioned captured emishi soldiers (fushû). As well the discovery of Form II
swords in interior part of the Tôhoku area suggests the migration of people from the Kantô area.
However, there were also Form III swords found in Nagano and Gunma Prefecture but they are
rather special cases and indicate an advancement within the then central culture of Japan.
Masakuni states that the known warabite-tô with the longest blade measures 58 cm in its nagasa, but the average length is around 46 cm, which would rank them among wakizashi according to the classifications we use today. Short warabite-tô with a nagasa between 30 and 40
seem to be the most old-fashioned ones, chronologically followed by medium-sized swords with a
blade length between 40 and 50 cm, mostly excavated in the Kantô and Chûbu areas. All longer
warabite-tô (i.e. with a nagasa of more than 50 cm) were discovered in the Tôhoku area and on
Hokkaidô. The sori started as curvature of the hilt only (tsuka-sori) and moved gradually up over
the tsuba area to the blade itself. A tsuka-sori can be seen on Form I and II warabite-tô, especially Form I swords show a strong curve along the hilt as well as on the blade. Such warabite-tô give
the strong impression that their are somehow related with the later nihontô, and this concerns
especially the kenukigata-gatana.
Almost all the excavated Warabiteto are badly rusted, but
when examining the surface of such remains, we learn that the mune section consists generally
of three layers. 88 matching the results Suenaga achieved on chokuto and that we‟ve already discussed and also suggesting that Kanto and Tohoku smiths adopted the Chinese complex construction
methods,
either learnt from the
western regions of
Japan or imported
through “The Northern
Route“. Conclusions
can be drawn about
the composition of the
shingane from the differences in carboncontent. They suggest
that a rather soft core
was inserted between
layers of kawagane
with an higher carboncontent. This kind of
construction is known
Fig. 17
as “makuri-kitae“ in
the construction of nihontô, confirming Suenaga‟s statements that this kind of forging method
was already known and applied in very early times. BHowever not all warabite-tô were constructed this way. Other examples were not forged by joining together layers of different steels but by
forging a certain piece of steel just by itself, so to speak in “maru-kitae-manner“. 89
The kitae of warabite-tô can be either of a maru-kitae kind, or of a combination of steels with
different carbon content (i.e. awase-kitae), whereas maru-kitae are rather limited and only seen
on some Form II swords in kissaki-moroha-zukuri. Awase-kitae is also seen on shorter swords
but mostly on examples excavated in the Tôhoku area and on Hokkaidô. Because of the corrosion, the back of such blades reveals three layers, and in most of them, the softer shingane is
lost and only a cavity remains. The jigane of warabite-tô is rather soft and does not come up to
the hardness of a nihontô as we know it. The carbon-content of the kawagane of Form I warabite-tô is about 0.2 to 0.3 %, which is rather equal to a nihontô´s shingane, and does not even
come up to the half of an usual kawagane of the latter. Consequently, the shingane of these warabite-tô comes with 0,07 % carbon close to pure iron. Further, there can be coarse-grained iron
slags seen in the shingane. They also occur in the kawagane but much finer. It is difficult to
apply yaki-ire to a soft steel with low carbon-content. A proper quantity of hardness is necessary
to increase the resistibility against a shock. A repeated adding of strength thru smithing and hardening increases the overall toughness of the steel. This can also be seen on swords from the
early Kamakura period, and the smiths who made warabite-tô grasped very well these principles. However it is next to impossible to apply a homogeneous yakiba on a steel with low carbon-content, and this is about the same starting position as retempering a blade which was damaged by fire, because such a saiha treatment results in most of the cases in a very soft yakiba. 90 The yakiba of warabite-tô is not very hard, that means in terms of Vickers generally about
300HV to 350HV. Later nihontô measure from 500HV up to 1200HV, The hardness of the following specimen was examined by the Vickers method (H.V. kg/mm500g) :
- Exacavated in Negishi, Kurihara district, Miyagi Prefecture (Form I) 145HV~192HV
- Iwate Prefecture, exact place of excavation unknown (Form I) 151HV~182HV
- Handed-down in the Ômiya-Iwatsutsumi-jinja, Agatsuma district, Gunma Prefecture
(Form II) 168HV~187HV
The steel can be therefore classified as austenitic, and is obviously of a softer composition than
the perlite and/or sorbite structure of nihontô which has a hardness of about 200HV to 300HV.
However, although they are constructed of softer steel, this softer steel is ductile, and this is the
peculiarity of such swords, because a moderate heat-treatment (yaki-ire and yaki-modoshi) was
applied to them, resulting in a soft but durable blade with a certain edge retention. When looking
at the jigane of Form I warabite-tô excavated in the Tôhoku area, first of all the clear colour of
the steel attracts attention and the jihada is a fine ko-itame tending to nashiji-hada, overflowing
with subtle ji-nie. Such a kind of soft looking jigane reminds one of the swords of Bungo Yukihira
from the early Kamakura period. Masakuni tried to polish a Form II warabite-tô which was handed-down in the Kantô area . It showed a maru-kitae but was not folded many times, that
means a trend towards a coarse forging method was noticeable. The jihada was an ô-hada,
consisting of large whirlpools, dull chikei, and nie-utsuri, but in between, there was also in places a soft and clear muji-hada remaining. These areas showed weak ji-nie and were somewhat
blackish. The same characteristics can be seen on the sword from Nakatoyooka that has an all
over dull appearance but with many clear hada areas in between and very strong ji-nie. A Form
III sword is the warabite-tô from the Shôsô´in as well as a kissaki-moroha hira-zukuri warabitetô found in Daimon in Nagano Prefecture. They have an unspeckled kitae in itame-hada mixed
with ô-hada, which tends to masame towards the ha.
The iron itself is rather soft, whitish, and has plenty of fine ji-nie. The chikei and other hataraki are entirely homogeneous and do not show that rustic appearance to be seen on swords
found in Tohoku and Kantô provinces. This speaks for a one step forward to a refined forging
skill. 91 As already seen, the yakiba of warabite-tô is not very hard and some seem to have no
yakiba at all, but after a closer examination of the jigane of such pieces, fine ji-nie occur in a
speckled manner. That means such blades are nevertheless hardened but have a very soft yakiba. There are also blades without a yakiba at all, but there are traces that they were once
equipped with a separate cutting edge (tsuke-ba). However, some blades seem to have experienced repeated re-tempering such as the Warabite-tô excavated in Negishi, Kurihara district,
Miyagi Prefecture in the possession of Mr. Matsumori Meishin, City of Tsukidate in Miyagi Prefecture or the example excavated in Iwate Prefecture (exact place of excavation unknown), in
Masakuni„s possession, or the so-called „Maigusa-tachi“ (nagasa 77,3 cm, sori 2,5 cm), Kanagawa Prefecture. 92 In old documents on swords 93 Masakuni found out that additional measures
to increase the hardness of a cutting edge – that means not only by applying a yakiba – were
applied to softer steels. This is described by the term “uzumi-yaki“ , which means to fire an object by inserting it completely in hot ash. This might suggest that with this additional measure,
eventually warabiteto were heated by sinking them entirely in hot ashes of the cooled charcoal
fire. It Seems to be the description of a re-hardening at lower temperatures, around 400° C. Six
Form I warabite-tô from the Tôhoku area up to Hokkaidô were polished, and each of them was
hardened with uzumi-yaki. Among such swords in uzumi-yaki, there are examples with an extremely soft hitatsura-like yakiba, and also pieces in which it seems that the kissaki area was retempered. All of these blades don´t show a hamon the way we know it, but rather a strong utsuri. All this might suggest the swords were hardened without (or with poor) clay cover, and that
the difference in hardening between the mune and the ha is due only or mainly in the difference
in cooling rate caused by the different thickness of the blade. It is possible that this process later evolved in the one that present day Tosho suggest is at the origins of Kamakura Choji Hamon achieved without clay but with better steel, better smithing skilfullness and higher temperatures.94 Two Form II warabite-tô which were excavated respectively in the Kantô and Chûbu
areas tell us more about the hardening process. One of them is the piece which was handeddown in the Ômiya-Iwatsutsumi-jinja. It has a strange midareba and vehement hataraki within
the ha, making it looking at a glance like a Sôshû blade from the Nanbokuchô period. It has
further a deep nioiguchi, a deep bôshi whose kaeri runs back in a long manner. Towards the
cutting edge, it resembles other ancient swords, which means it is dark but has clear areas
without hataraki, sunagashi-like nie structures running through the ji, and in places spot-shaped
hardening effects which are dark in the center. This sword was obviously hardened by applying
tsuchi-tori, but it seems that the impetuous hardening effects result from a peeling-off of the clay
(Fig.18).
Fig. 18
In terms of Vickers, the hardness of the yakiba measures 380HV at the nioi structures, 546HV
at the nie structures, 906HV at the granular dot-shaped nie structures, and 1046HV at the dark
and isolated ara-nie spots. The other piece is a warabite-tô excavated at Nakatoyooka.
Although it might have something to do with the removal of the deep rust, the hardening along
the kissaki area is rather weak, but there are nevertheless traces of a yaki-ire treatment visible
around the base of the blade.
In this respect, this blade has similarities to the hitatsura of the aforementioned piece. 95 Then
Masakuni discusses two Form III warabite-tô. One of them comes from the Shôsô´in . This blade has a hamon based on hoso-suguha which starts with a yakidashi about 6 cm in front of the
machi area. It shows plentiful nijûba and hotsure, nie, soft and suppressed nioi (i.e. with uruoi),
and minor kinsuji-like linear hataraki. The bôshi is somewhat speckled but seems to be a komaru with a kaeri which runs back shallowly along the mune. The second piece is the kissakimoroha blade from Daimon in Nagano Prefecture. It is nearly of the same kind as the Shôsô´in
warabite-tô, which means it has a somewhat dark hoso-suguha which starts in a yakidashi
about 4 cm in front of the machi area. A nijûba runs rather continuously from the center of the
blade up to the kissaki. The nioiguchi is somewhat weak, very tight, and contains ko-nie. The
bôshi is a kind of speckled ô-maru tending somewhat to kuzure, and there are traces of a shallow but continuous yakiba running back down the mune. As a conclusion Masakuni suggests
that even when looking at such a limited number of examples, each of them showed a jiba with
complex variation. Form I blades consists mostly of softer steel, tending to be muji-hada with
utsuri in uzumi-yaki and nie-utsuri. Form II blades have intense ji-nie, ô-hada, and a hamon
which tends from midare to hitatsura. Form III blades show a very regularly forged itame-hada
mixed with masame, and a hoso-suguha hamon. When we look at the jigane of polished warabite-tô we can ascertain that they already show a local characteristic in the way of forging, like
we differentiate between Yamato, Bizen, Yamashiro, Sôshû, and Mino discussing later nihontô.
The differences in these three sword forms suggest either a different approach or tradition in
forging, or considerable regional variations of the latter. 96
At the time when the warabite-to was becoming obsolete , swords with ryûko-zuka („drumshaped hilts“) emerged, followed by the appearance of kenukigata-gatana and kenukigata-tachi,
leading eventually into the time of swords with a generally long nagasa and sori. 97
From Chokuto to Wanto
These terms refers to straight and curved swords, respectively, and Masakuni gives us an interesting and detailed description of the blades that belong to each category. Tachi written with
the characters 大刀, ô-tô and other ancient swords are usually referred to as „chokutô“, literally
translated „straight sword“, and tachi written with the characters 太刀 and katana which emerged
in the Mid-Heian are referred to as „wantô“, literally „curved sword“. Tôsu are counted to the
group of chokutô, and koshigatana or tantô emerged in wantô times even if straight. In any difficult to decide case, the classification follows this tradition. In this sense, the traditional classification according to extant examples is as follows: 98
chokutô: tôsu, hira-zukuri chokutô, katakiriba chokutô, kissaki-moroha hira-zukuri chokutô,
kissaki-moroha kiriba-zukuri chokutô, shinogi-zukuri chokutô (i.e. tachi [大刀] and ô-tô),
ken
wantô: warabite-tô, swords with ryûko-zuka, kenukigata-gatana, kenukigata-tachi, hira-zukuri
uchigatana, kissaki-moroha shinogi-zukuri tachi (i.e. kogarasu-maru-zukuri), early tachi
(mumei), tachi (signed), emishi swords, hira-zukuri wakizashi, shinogi-zukuri wakizashi,
shinogi-zukuri uchigatana, koshigatana (i.e. tantô), ken
Masakuni states that Ken are classified as belonging to both cathegories cause they were produced over a very long period but I wonder why Karayodachi that were and are produced during the same period aren‟t, notwithstanding both have a ceremonial use mainly as offerings to
shrines and anyway not for practical pupose.
As we can see, the differences of chokutô and wantô can be found in the tsukuri-komi, the
shape of the nakago, the characteristics of the jiba, but first and foremost in the presence or
lack of a sori. As the name “chokutô“ suggests, such blades and their nakago are principally
straight, and in wantô like tachi and katana, a distinct sori occurs in the blade and in the nakago.
As seen using the above given classification, swords of the category chokutô were in use in ancient times, and wantô swords emerged somewhere around the Middle Heian period. So it is
quite natural to think that wantô are a logical advancement or rather a further stage of the chokutô, and there were also shinogi-zukuri chokutô swords excavated which date even back to the
Nara and preceeding Kofun period. However, it is still a question if this development to wantô
took place immediately, because there are no accurate reference materials which can be drawn
on as indicative for this process. Masakuni however is convinced that already in the Nara period, the emergence of warabite-tô – which are of a different category then chokutô – opens the
period of wantô. Actual kenukigata-gatana and the shortly afterwards developed kenukigatatachi enter the category as well. During this development process that can be seen as an evolutionary one (Fig.21), it is very likely that the swordsmiths who made chokutô were naturally
affected by intercourse and cultural exchange with eastern specialists. It is surprising that the
tachi-sugata as we know it today was developed with such a delay, that means somewhere between the latter half of the 10th up to the 11th century. Well, when looking at the later „katana“
bearing such swords in mind, it can be easily grasped that warabite-tô or kenukigata-gatana
and ryûko-zuka – where both the blade and the hilt are made of the same piece of iron – are
almost the roots of the former, and that the later katana-sugata is close to certain sword forms
which were already used in the Nara period. Relics which could be seen as forerunners of the
later tachi date back to the Heian period, namely the kenukigata-tachi 99 being the starting point.
However, there are nearly no pieces extant which indicate that they were mounted with wooden
hilts, only the gyôbutsu Kogarasu-maru,a tachi, mumei, attributed to Den Amakuni, nagasa 62.7
cm, sori 1,4 cm, nakago-sori 3,3 cm,100 from the Heian period and other old tachi, as for
example a tachi mumei, nagasa 73 cm, sori 0,8 cm, nakago-sori 4 cm, in the possession of the
Udo-jingû or a tachi, mumei, nagasa 78.2 cm, sori 2, cm, nakago-sori 4,3 cm, in the possession
of the Ôyamajimi-jinja were mounted this way. The emergence of signed tachi has to be seen
as subsequent to such swords. The transitional time from chokutô to wantô is still rather ignored
in the studies on early swords, but we can suggest that the former half of this trend started somewhere in the mid 8th century, which is clearly substantiated by reference materials like warabite-tô and swords of the same kind. The latter half started in the late 9th century with rather
short kenukigata-gatana, nagasa 47 cm, sori 1,5 cm, nakago-sori 3 cm, in the possession of the
Hokkaidô University Museum, Sapporo or a kenukigata-gatana, nagasa 50 cm, sori 1,5 cm, nakago-sori 3 cm, in the possession of the Gojôme Community Center, Akita Prefecture coming
close to a tachi-sugata, and the emergence of the kenukigata-tachi in the 10th century can be
regarded as the completion of this transition. 101 It is not clear if the kenukigata peculiar handle
was introduced for practical or ceremonial purposes. Maybe the former developed into the latter. Under a practical point of view it can be suggested such a tang was intended to dissipate
shocks produced when striking an hard target with a slashing motion, before such shock could
reach the hand and whirst, or simply to make the blade lighter. In this case it was possibly
wrapped with a string of soft material, possibly leather or silk, to improve the grip. Under the
ceremonial point of view it can be suggested it was a sort of status symbol, exclusively for distinguished soldiers, and consequently not covered to show the status of the owner.
Fig. 19
1) Ken, 2) Tōsu, 3) Hirazukuri Chokutō, 4) Hirazukuri Chokutō with wide mi-haba,
5) Warabitetō, 6) Kiriha Zukuri Chokutō, 7) Kissakimoroha Hirazukuri Chokutō,
8) Kissakimoroha Kirihazukuri Chokutō, 9) Shinogizukuri Chokutō, 10) Kenukigatagatana,
11) Ryukozukatō, 12) Kenukigata Tachi, 13) Emishitō, 14) Ko-Tachi (古太刀, old Tachi),
15) Hirazukuri Katana, 16) Signed Tachi, 17) Signed Shinogizukuri Wakizashi,
18) Signed Shinogizukuri Uchigatana, 19) Signed Koshigatana (Tantō),
20) Signed Hirazukuri Kowakizashi
Early Swords Shapes designed in Japan
after classical WarabiteTo according to Masakuni Ishii
Transitional between WarabiteTo and EmishiTo
Kenukigata-like WarabiteTo
Evolved Kenukigata-like WarabiteTo
Kenukigatagatana
Kenukigata Tachi
RyukozukaTo
EmishiTo
O-tosu
Fig. 20
The latter possibility matches with the low number of kenukigata warabiteto and kenukigata
katana found and with the use that was made later of kenukigata tachi. We know that the Minamoto branch of the Seiwa Fujiwara was tied to the Kanto. The famous portrait of Minamoto no
Yoritomo wearing a Kenukigata Tachi seems to indicate this old type of mount had a special
meaning to him or to the court, stronger then the common Efu Tachi court sword of his period.102 There are still discussions on the theory that the kenukigata-tachi is the prototype of the
later tachi, but the characterstics of the former – that means the sori of hilt and blade – was also
a characteristic of the contemporary warabite-tô, as was the kenukigata sukashi opening along
the center of the hilt. Further, there were remnants of kenukigata-gatana discovered which date
back to the late 9th century. This sword form is with its deep sori very similar to warabite-tô, and
it seems that the kenukigata-gatana is a further stage of the latter. The curve of the hilt reached
its end, and the sori moved from the hilt section gradually up towards the blade, whereas the
nagasa of the blade itself was elongated too and got more slender. This eventually resulted in
the manoeuverable and quick kenukigata-tachi (with a blade length of more than 60,6 cm, i.e. 2
shaku), and I would like to refer here to a very good example of this kind of sword, excavated in
Sôga in Shiojiri city (Nagano Prefecture). This kenukigata-tachi shows already a magnificent
tachi-sugata, but is still mounted with a thick iron hamidashi-style tsuba identical to those used
on warabite-tô. It has no habaki and fits to the saya due to the strong funbari towards the base
of the blade. It is in hira-zukuri with kaku-mune and fukura along the kissaki. It has a tomotetsuzuka with an ancient kenukigata sukashi opening. This sword points at a glance towards a
dating into the latter half of the 10th century, but
on the basis of the accompanying grave goods
like hai-gusuri (ash glaze) ceramics and eightlobed bronze mirrors (hachiryô-kyô), this dating
can be fixed to the Eien period (987-989). Chronologically subsequent kenukigata-tachi were
excavated in Saito city´s Tsuma, Miyazaki Prefecture, and in Washimamura in Niigata Prefecture. They are already in an efu no tachi manner
with a small ana for mounting an habaki, that
means we are entering the period where tachi
were by default mounted with a habaki. The time
difference between these two swords and the
kenukigata-tachi discovered in Soga is about a
century, and from the time subsequent to this
period, we already have the opportunity to look at
handed-down and preserved pieces, like the kenukigata-tachi from the Dazaifu-jinja, Fukuoka
Prefecture. The latter tachi has a removable hilt,
and the tachi preserved in the Kasuga-taisha and
Fig. 21
Ise-jingû come with a magnificent tachi-koshirae
and seem to be classified as efu no tachi from the end of the Heian period intended to be worn
by imperial guards (gijô).103 It is thought that the use of the sukashi opening along the center of
the hilt of kenukigata-tachi with tomotetsu-zuka serves as an anti-shock measure in the hilt area
upon impact of the blade. The „Kanchi´in-bon“ (from the Shô´an [ 1299-1302] to Ôei periods
[1394-1428]) notes the term „sansun imu hi“ (三寸忌樋), lit. „9 cm removed channel“.
So it is possible that this term refers to the sukashi opening in the hilts of kenukigata-gatana, kenukigata-tachi, and warabite-tô, and when looking at where the author uses the term, we learn
that it is mostly in sections dealing with fushû swordsmiths. That would mean that these fushû
swordsmiths and other old smiths from the nothern Ôshû regions made the prototype of this peculiarity. The „Kanchi´in-bon“ mentions a certain swordsmith called „Minamoto Fujitsugu“ (源藤次)
who came down from Yamanome in the northern Ôshû region to Numa in Sagami province, and
made their kenukigata-tachi. It is also stressed that he made also tachi in suguha with characteristics of Yamato-Den.
Fig 22
This might be an important point. Still a question is, “What is the earliest extant tachi with a
sori?“, and mostly in this
connection, the gyobutsu Kogarasu-maru from
the early Heian period is
mentioned. However, if
this sword would really
dated to the early Heian
period, this theory would
not be in question, but
the tsukuri-komi in kissaki-moroha-zukuri and the
characteristics of the jiba
are typical for the workmanship of swordsmiths of central Japan. Probably it must be regarded as a work of the KoSenjû´in school (from the Yamato tradition), but the shape of the sword with regular sori along the
blade, the naginata-hi, as well as the sori and shape of the nakago looks very similar to tachisugata of the Kamakura period. On the other hand, the size and position of the mekugi-ana, and
the finish of the nakago-jiri as ha-agari kurijiri has something in common with the tangs of extant
signed tachi from the very late Heian period. The characteristics of the jiba are very ancient and
would speak for an even more ancient period and the name „Kogarasu“ might suggests an affiliation with the so-called „Kumano Faith“ (Kumano-shinkô).104 Masakuni suggests that Taira no Kiyomori (1118-1181) once offered this sword to the deity Kumano-Gongen which is worshipped on
one of the Kumano-sanzan. But if we assume that this sword dates from around the Hôgen period
( 1156-1159), we come up with a time difference of about two or three centuries to other, earliest
kenukigata-tachi. Except for this sword, in my knowledge there are no other tachi from the early
Heian period extant which are mounted with a wooden hilt, but when looking at extant wantô except for kenukigata-tachi, we have a certain vacuum between the production time of the latter and
curved swords in general. So it is very likely that tachi with wooden hilts were already in use during the missing period. As regards the origins of katana and koshigatana, especially hirauchigatana (i.e. short uchigatana in hira-zukuri) which followed, ryûkozuka swords must be taken
into consideration. Today, we have six ryûkozuka swords which were excavated in Iwate Prefecture, all of them – as well as fragments – date from the early to middle Heian period. These
swords are basically hira-zukuri katana with a broad mihaba and elongated kissaki, and a sori
along the hilt and the blade. The hilt itself is of tomotetsu-zukuri and strongly tapers around the
center.
This is why the hilt form got its name, it resembles namely a small hand-drum (ryûko 立鼓)
which narrows considerably towards the center. The tip of such hilts has a square hôto shape
(方頭), and a hole for threading a cord is opened in between. There are fragments of shitodome
extant which have a gilded bronze fukurin. This interpretation of the kashira section of the sword
is similar to warabite-tô and hôto no tachi (方頭大刀, lit. „square pommel swords“), and their places of discovery indicate that they were produced in the same areas as the latter. Emishi
swords are regarded as being chronological subsequent, and examples which explicitely show
this development are the swords excavated in Hokkaidô Sapporo´s Maruyama (円山). According to the description in the „Kanchi´in-bon“, the emishi sword which was discovered on top of
Fujiwara no Kiyohira´s (1056-1128) coffin, seems to be classified already as being made by
fushû swordsmiths presumably Mokusa school (Fig.23).
Also, maybe the “Hige-giri“ (髭切), the heirloom sword of the Minamoto family, has the same
origin. This convinces me to agree with Masakuni in stating that the forerunner of the hirauchigatana were the aforementioned emishi swords, which were made in this ancient form,
without changes, until the Heian period. It„s now time to discuss daggers. It is thought that koshigatana (i.e. tantô) were a further development of earlier tôsu, but there were also naginata in
Fig. 23
tôsu-shape, and the similar tomotetsu-zuka curved daggers (magari-tôsu) were frequently found
together with tôsu with wooden hilts as grave goods. This suggests that both tôsu forms were
used simultaneously. The development from tôsu to koshigatana can be very well understood
via the koshigatana-like ô-tôsu discovered at the excavation places of Kumadô , Nekoyachi,
Akutsu , Shikama and others. Most pieces have a kaku-mune, a quite crude nakago, a kissaki
with fukura, strong funbari towards the base of the blade, no machi, and no sori. Ô-tôsu excavated in Hokkaidô´s Ebetsu, Eniwa, Moroyo, and the like date somewhat later and have a kamasu
-kissaki, funbari, two machi, and a shallow sori. This suggests that blades of this category with
kamasu-kissaki date later than those with strong fukura. Masakuni states that ô-tôsu with kamasu-kissaki were found at several places in the Tôhoku area, and they already show a blade shape which could be regarded as the precursor of Kamakura-period koshigatana. Their nakago
have a small mekugi-ana, and there are pieces where an iron mekugi is extant. Each nakago
shows a tsuchime finish and thins and tapers towards the nakago-jiri. However there are also
identically shaped blades with shallow funbari, but according to the tôsu without habaki and kaku-mune which were found in the coffins of Kiyohira and his son Fujiwara no Motohira
(1105~1157), the first appearance of koshigatana can be suggested as happening at the end of
the Heian period. When looking at works from the early Kamakura period, also the koshigatana
by Yukihira has a wide mihaba and shallow sori, and the tip keeps a kamasu-kissaki.
Further, the tantô which was found in the cavity of the Amida Buddha statue of Hiroshima´s Ankokuji (安国寺 Fig.24) – the statue bears the date inscription of the eleventh year Bun´ei (1274)
– has a kamasu-kissaki too as well as an ancient and small mekugi-ana.105
Fig.24
Tachi evolution according to Masakuni
Fig. 25
Again discussing the emergence of curvature in central Japan, Dr. Honma Junji states :
“…Omissis… There are also some swords in Kogarasu-zukuri. Shallow sori is recognised in
them,… Omissis
I have already mentioned that there are kissaki-moro-ha-zukuri amongst the swords of the Shōsōin Depository similar to so-called Kogarasu-maru-zukuri. As the original Kogarasu-maru has
deeper sori and narrower shinogi-ji, this means that the sword was made later than those of the
Shōsō-in Depository. Thus it is speculated that Kogarasu-maru is one of swords made in the
Heian Period but the nioi-guchi and the hataraki of the ji and ha closely resemble those of the
swords in the Shōsō-in Depository. After all, Kogarasu-maru should be recognized as a very early
work, inferring from the workmanship“.106
The presence of a shallow Sakizori (more pronounced toward the point) on some of the Kissakimoroha swords in the Shōsō-in is indeed puzzling. But the curvature, as we‟ve seen, started
into the hilt and then was progressively applied to the blade as well. So, why does what resembles early examples of Kogarasuzukuri show such a strange sori with no curvature in the tang ? It
might be a byproduct of hardening, but it is strange for such an inaccuracy that could have been
fixed later in the smithing process on such otherwise excellent examples of swords. There is also
an example with short Nagasa and shallow curvature along the whole blade preserved in the Tokyo National Museum and attempts were made also of mixing warabiteto and Kissakimoroha
tachi, attempts possibly made by smiths of Emishi origin that had moved to the western provinces
and trained in western Japan‟s more adanced smithing. I think that Mr. Honma is right in giving
more weight to the similitude in workmanship rather than the shape between “Amakuni‟s Kogarasu” and the ones in the Shōsō-in. I think that the sori, when present, in these early swords is the
result of attempts made during the time in order to obtain
a more functional shape,
adding sori only to the tang,
only to the point, adding a
central ridge, elongating the
double edged part in proportion to the whole blade
length, diminishing or elongating the whole blade length
and so on (see Fig.26)maybe
mimicking what happened
also to Shinogizukuri ones in
the very same period. The
exception can be raised that
these double edged blades
were intended for court or
ceremonial use only, while
the ones in Shinogizukuri remained the utilitarian type.
In my opinion, in an age of
transition, these swords represent a branch that got extinct notwithstanding the attempts of improvement, leaving just a few examples
whose shape proved to be
less effective then Shinogizukuri that we know today.
Fig. 26 Pictures not in scale with each other.
Another interesting theory about the rise of curvature in Nihonto is the one suggesting that the
curvature was first achieved by chance when applying the clay-coating process to Shinogizukuri
straight blades. 107 This theory is based on the mechanical deformation a sword is subject to
during the above mentioned hardening process. In fact, applying an insulating means to all the
surface (but the edge) of a straight ridged sword, heating it up and then suddenly cooling it in
water will produce a mechanical stress that results firstly in a downward curvature (Gyakuzori)
that with progressive cooling changes to an upward curvature, due to both the difference in
thickness of the different parts of the swords and its final crystal composition (see fig. 27). Even
if it has a solid scientific basis this theory, in my opinion, is still not appropriate to justify the addition by chance of a curvature to the Shinogizukuri straight Tachi. To begin with, we‟ve seen
that the curvature was firstly applied to the tang of Warabiteto (and soon after to Jokoto but still
before the appearance of a curvature in the blade). The tang is notoriously not affected by the
hardening process, meaning that such curvature was surely intentional. Karl Friday confirms the
first curved swords appeared in Japan are the Warabiteto with their curved tang. 108 Then we
have the undeniable fact that differential hardening using an insulating means was already in
use in Japan far before the introduction of curvature and was applied to blades with the same
cross section and general shape that later
would result in a “modern” curved Tachi.
Thirdly we have to consider that curvature
induced by Yakiire to a straight blade is not
as deep as many curvatures we can see in
ancient Nihonto (some have to be shaped
with a curve before the Yakiire and it may
happen that the curvature has to be emphasized on the copper anvil according to the
task of the smith). Finally we have to consider
that the curvature in early curved Tachi is
placed near the handle, in a very ergonomic
position, when an unintentional attempt would
have given us something more “random”. It
can be suggested that the strong Funbari
proper of early Tachi might affect the position
of curvature due to the fact that more material
is present near the handle, while the slimmer
upper part remains almost straight. Or that
the change happened when the japanese
started to move the Shinogi upward away
from the edge, making the sword more prone
to curve-up while the previous position of the
ridge, closer to the edge, stopped such a tendency. Still it doesn‟t convince me for the folFig. 27 Changes in shape during Yakiire process. Top at
lowing reasons. I believe the early smiths in
higher temperature, bottom after cooling.
Japan were already aware of the deformations the differential hardening process gives to a blade. Everybody that has had the luck to attend at a basic lesson of traditional swordmithing in Japan has been confronted with the smithing of a Kogatana, the small utility knife usually placed in the side of the scabbard. This is a
straight blade, thin, with no ridge (Hirazukuri). To apply the differential hardening process and
obtain a straight blade, you have to smith a blade with reverse curvature. When the hardening
has been successfully performed the blade should show an almost straight shape due to the
upward deformation as mentioned above and eventual adjustments are made on an hot copper
anvil.
The polisher will give the final perfectly straight appearance to the Mune (back). So, to obtain a
straight sword might be harder than obtain a curved one, even when the cross section is without
ridge. The forefather of Kogatana is called a Tosu (Fig.12) and is well represented in the Shōsōin with many examples, most of them showing a skillfully executed Suguha with Yakiotoshi,
meaning that the clay-coating process was performed with these blade as well, the same way
as modern Kogatana. Hence we can infer the process had to be the same, starting from a blade
with reverse curvature. This implies that the thermodynamic process to which the blade is subjected to during the Yakiire was already known and mastered in these early times. Maybe errors
produced curved swords, but this would have happened in a time when such curved swords
weren‟t needed yet and consequently were discarded. Likely such errors didn‟t happen in Japan, that had learned the already established technology of differential hardening from the continent. The above mentioned thermal stresses apply to every sword so to produce Chokuto it
would have needed the same attention that Tosu required. Of course the experience in dealing
with thermal stresses and modifications proved to be useful later in order to apply a curvature to
swords , but only after the concept of intentional curvature was well present in the Japanese
smiths intentions, as is highlighted by Nakago evolution.
Fig. 28 Tosu preserved in the Shōsō-in
The exact reason of the emergence of a curvature in Nihonto is still a debated matter and the discussion includes several factors that might be not exclusively related to horseback fighting. Masakuni, after having excavated and studied more then 300 chokuto, states
“Compared to the blade, all these nakago made a somewhat weak and unsubstantial impression.
Such a short and small nakago was made in order to avoid a breaking-off of the affixed wooden
hilt when stabbing with the sword. But it suggests also that such swords with uchizori along the
blade and nakago were not that much intended for cutting movements. 109
However I‟m still convinced that single-edged Chokuto, especially the ridged ones, were engineered to be also slashing weapons, with only one side sharpened and with a rectangular back
that gives more resistance to frontal shocks and lateral stress due to an imperfect angle of cutting. They are believed to be appreciated in China as backup weapons for cavalry, notwithstanding they are straight. A possible explanation is that curved NihonTo simply proved to be better
then straight ones after having made many attempts in applying the new idea of curvature encountered during the wars against the Emishi, renowned for their skillfulness in fighting from
horseback, in the continuous attempt to improve weapons that the military class has always
made, following the “Counter Response and Symmetry” theory. If this was due to the shift of fighting tactics from mainly based by foot to mainly based by horseback, it can only partially explain
the matter. For example, a curved sword is more resistant to frontal shocks due to its curvature
and the slashing results more effective because a longer part of the cutting edge enters in contact
with the target during the cutting motion, following the arc designed by the arm. These advantages are valuable in fighting by foot as well and, as we already know, back then the main
weapon in horseback fighting, both by Yamato troops and by Emishi, was the bow. It is interesting
to note that in central Asia the emergence of a curved sword for cavalry use is almost contemporary (possibly slightly earlier) to the appearance of WarabiteTo, but so far I‟ve not been able to
find good enough evidences about direct influences from there to Bando or Tohoku via “the
Northern Route”.
It‟s a possibility that needs further studies before it becomes a theory. So far, I‟m more comfortable in supposing that Eastern Japan, especially the Kanto, having reached an evolved enough
situation, was able on its own to produce a short curved sword fullfilling the requirements for an
agile fight from horseback and that this sword was common in Bando and Tohoku for more then
a couple centuries, until the “pacification” by the hands of Yamato troops, sustained by collaborative Emishi, unified the whole of Japan under a unique cultural model. Today we are used to
associating curved swords to horseback fighting as their shape is effectively well-suited to such
a type of warfare. Anyway the fact that curved swords appeared so late in central Asia given the
amount of time since the invention of horse riding, the stirrup and iron furnace and notwithstanding nomadic populations revered the horse as a way of life and had in horseback fighting their
main source of income and defense, makes me think that the matter is not as simple as we see
it today. Maybe such a simple and easy enhancement as the curvature looks simple and easy
to us and today, but to achieve it starting from nothing wasn‟t as obvious as seems now.