Before the Tachi: Swords of Japan's Kofun, Asuka, and Nara Periods and the Origins of the Japanese Sword

Japan's Earliest Swords: Kofun to律令

Iron implements arrived in Japan during the Yayoi period (c. 3rd century BCE), brought from continental Asia along with bronze culture. The swords of this era were straight-bladed (chokuto), directly imported or copied from Chinese and Korean models.

By the Kofun period (3rd–7th centuries CE), iron swords and blades were routinely interred in burial mounds of the powerful. Most were still straight continental forms, though distinctly Japanese decorative elements began appearing on handles and scabbards. The most famous example is the iron sword with 115 gilt-inscribed characters from the Saitama Prefecture Inariyama Kofun, dating to the 5th century.

The Taiho Code of 701 CE placed sword manufacture and possession under state control, standardizing weapons for officials and military forces. Nara period (710–794) swords ranged from ornate ceremonial weapons — many preserved in Shoso-in treasury at Todaiji — to functional combat blades, all showing strong continental aesthetic influence.

The Revolutionary Shift to Curved Blades

The most momentous transformation in Japanese sword history occurred in mid-Heian period (794–1185 CE): the emergence of the curved tachi. Multiple factors drove this change: the development of mounted cavalry tactics, where curved blades proved easier to draw and more effective for downward strikes from horseback; improved forging techniques enabling consistent production of complex curved forms; and the rise of eastern warrior clans whose combat experience shaped demand for new blade geometry.

By the late 10th to 11th century, the tachi had achieved its recognizable form, and regional smith clusters were forming in Bizen, Yamashiro, and Yamato — the seeds of the Five Traditions. This marks the beginning of what scholars call the koto (ancient sword) period and the true birth of the nihonto as a cultural form.