Evolution of the SwordBefore 987, examples of Japanese swords were straight chokutō or jōkotō and others with unusual shapes. In the Heian period (8th to 11th centuries) sword-making developed through techniques brought over from China through trade in the early 10th century during the Tang Dynasty and through Siberia and Hokkaidō, territory of the Ainu people. The Ainu used warabite-tō (蕨手刀) and these influenced the nihontō, which was held with two hands and designed for cutting, rather than stabbing. According to legend, the Japanese sword was invented by a smith named Amakuni (ca.700 AD), along with the folded steel process. In reality the folded steel process and single edge swords had been brought over from China through trade in the early 10th century during the Tang Dynasty. Swords forged between 987 and 1597 are called kotō (古刀) (lit., "old swords"); these are considered the pinnacle of Japanese swordcraft. Early models had uneven curves with the deepest part of the curve at the hilt. As eras changed the center of the curve tended to move up the blade.
The nihonto as we know it today with its deep, graceful curve has its origin in shinogi-zukuri (single-edged blade with ridgeline) tachi which were developed sometime around the middle of the Heian period to service the need of the growing military class. Its shape reflects the changing form of warfare in Japan. Cavalry were now the predominant fighting unit and the older straight chokutō were particularly unsuitable for fighting from horseback. The curved sword is a far more efficient weapon when wielded by a warrior on horseback where the curve of the blade adds considerably to the downward force of a cutting action.
The tachi is a sword which is generally larger than a katana, and is worn suspended with the cutting edge down. This was the standard form of carrying the sword for centuries, and would eventually be displaced by the katana style where the blade was worn thrust through the belt, edge up. The tachi was worn slung across the left hip. The signature on the tang (nakago) of the blade was inscribed in such a way that it would always be on the outside of the sword when worn. This characteristic is important in recognising the development, function and different styles of wearing swords from this time onwards.
When worn with full armour, the tachi would be accompanied by a shorter blade in the form known as koshigatana ("waist sword"); a type of short sword with no hand-guard (tsuba) and where the hilt and scabbard meet to form the style of mounting called an aikuchi ("meeting mouth"). Daggers (tantō), were also carried for close combat fighting as well as carried generally for personal protection.
The Mongol invasions of Japan in the thirteenth century spurred further evolution of the Japanese sword. Often forced to abandon traditional mounted archery for hand-to-hand combat, many samurai found that their swords were too delicate and prone to damage when used against the thick leather armor of the invaders. In response, Japanese swordsmiths started to adopt thinner and simpler temper lines. Certain Japanese swordsmiths of this period began to make blades with thicker backs and bigger points as a response to the Mongol threat.
By the fifteenth century, the Sengoku Jidai civil war erupted, and the vast need for swords together with the ferocity of the fighting caused the highly artistic techniques of the Kamakura period (known as the "Golden Age of Swordmaking") to be abandoned in favor of more utilitarian and disposable weapons. The export of nihontō reached its height during the Muromachi period when at least 200,000 nihontō were shipped to Ming Dynasty China in official trade in an attempt to soak up the production of Japanese weapons and make it harder for pirates in the area to arm.
In the 15th and 16th centuries, samurai who increasingly found a need for a sword for use in closer quarters along with increasing use of foot-soldiers armed with spears lead to the creation of the uchigatana, in both one-handed and two-handed forms. As the Sengoku civil wars progressed, the uchigatana evolved into the modern katana, and replaced the tachi as the primary weapon of the samurai, especially when not wearing armor. Many longer tachi were shortened in the 15th-17th centuries to meet the demand for katana.
The craft decayed as time progressed and firearms were introduced as a decisive force on the battlefield. At the end of the Muromachi era, the Tokugawa shoguns issued regulations controlling who could own and carry swords, and effectively standardized the description of a nihontō.
New swords
In times of peace, swordsmiths returned to the making of refined and artistic blades, and the beginning of the Momoyama period saw the return of high quality creations. As the techniques of the ancient smiths had been lost during the previous period of war, these swords were called shintō (新刀?), literally "new swords". Generally they are considered inferior to most kotō ("old swords"), and coincide with a decline in manufacturing skills. As the Edo period progressed, blade quality declined, though ornamentation was refined. Originally, simple and tasteful engravings known as horimono were added for religious reasons. Later, in the more complex work found on many shintō, form no longer strictly followed function.
Under the isolationist Tokugawa shogunate, swordmaking and the use of firearms declined. The master swordsmith Suishinshi Masahide (c.1750–1825); published opinions that the arts and techniques of the shintō swords were inferior to the kotō blades, and that research should be made by all swordsmiths to rediscover the lost techniques. Masahide traveled the land teaching what he knew to all who would listen, and swordsmiths rallied to his cause and ushered in a second renaissance in Japanese sword smithing. With the discarding of the shintō style, and the re-introduction of old and rediscovered techniques, swords made in the kotō style between 1761 and 1876 are shinshintō (新新刀), "new revival swords" or literally "new-new swords." These are considered superior to most shintō, but inferior to true kotō.
The arrival of Matthew Perry in 1853 and the subsequent Convention of Kanagawa forcibly reintroduced Japan to the outside world; the rapid modernization of the Meiji Restoration soon followed. The Haitorei edict in 1876 all but banned carrying swords and guns on streets. Overnight, the market for swords died, many swordsmiths were left without a trade to pursue, and valuable skills were lost. The nihontō remained in use in some occupations such as the police force. At the same time, kendo was incorporated into police training so that police officers would have at least the training necessary to properly use one.
In time, it was rediscovered that soldiers needed to be armed with swords, and over the decades at the beginning of the 20th century swordsmiths again found work. These swords, derisively called guntō, were often oil-tempered, or simply stamped out of steel and given a serial number rather than a chiseled signature. The mass-produced ones often look like Western cavalry sabers rather than nihontō, with blades slightly shorter than blades of the shintō and shinshintō periods.
Military swords hand made in the traditional way are often termed as gendaitō. The craft of making swords was kept alive through the efforts of a few individuals, notably Gassan Sadakazu (月山貞一, 1836–1918) and Gassan Sadakatsu (月山貞勝, 1869–1943), who were employed as Imperial artisans. These smiths produced fine works that stand with the best of the older blades for the Emperor and other high ranking officials. The students of Sadakatsu went on to be designated Intangible Cultural Assets, "Living National Treasures," as they embodied knowledge that was considered to be fundamentally important to the Japanese identity. In 1934 the Japanese government issued a military specification for the shin guntō (new army sword), the first version of which was the Type 94 Katana, and many machine- and hand-crafted swords used in World War II conformed to this and later shin guntō specifications.
