奈良時代の刀剣

The Nara period (710–794) established Japan's first fully codified imperial state under the ritsuryō legal codes, and sword production was systematized as part of the new military order. Straight swords (chokutō) derived from continental Tang Chinese and Korean models formed the standard military weapon of the imperial guard and provincial armies. The most extraordinary surviving evidence of this era's achievement is the collection of swords preserved in the Shōsōin repository at Tōdaiji, donated as part of Emperor Shōmu's personal effects. These blades—decorated with gold, silver, sharkskin, and lacquer in dazzling assemblages—demonstrate that Nara-era swordsmiths had mastered folded-steel construction and sophisticated heat treatment. They also show that the Japanese sword had already separated into two cultural trajectories: the fighting sword and the ceremonially loaded prestige object endowed with sacred authority. Continental metalworking lineages transplanted by craftsmen from Baekje and Silla took root especially in the Yamato region, establishing proto-smithing communities that would eventually develop into the great Yamato school. The Shichishitō (seven-branched sword) at Isonokami Shrine, a fourth-century Korean royal gift, embodied the tradition of the sword as sacred vessel—a spiritual understanding that deepened through the Nara period and became inseparable from Japanese sword culture thereafter. Technically, Nara swords represent the essential platform on which the curved Japanese sword was built: without the advances in steel refinement, differential hardening, and decorative metalwork achieved in this era, the transformative leap to the tachi would have been impossible.