Swords of the Asuka Period

The Asuka period (593–710) was a pivotal moment in history when the Yamato court underwent transformation into a centralized ritsuryo state, and this political upheaval profoundly influenced Japanese sword culture. Paralleling the active reception of continental civilization——Buddhism, Chinese writing, and the ritsuryo system——metalworking technology from the Korean peninsula and Chinese mainland flowed into Japan through toraijin (immigrant craftsmen and technicians), fundamentally altering the technical foundations of sword production.

The swords of Japan before the Asuka period belonged to the straight-sword (chokutō) tradition from the Yayoi and Kofun periods. Iron straight-swords transmitted from China and Korea around the fifth century formed the military core of the Yamato polity, but metalworking and forging technology at this stage remained heavily dependent on knowledge brought by toraijin. With the advent of the Asuka period, this technology began to take root and develop within Japan, and the prototype of Japan's distinctive "tatara" iron-smelting method began to be attempted in various regions.

The most important cultural artifacts from the Asuka period are the Shichishitō (Seven-Branched Sword) preserved at Ishigami Shrine (Tenri, Nara Prefecture)——strictly speaking, a fourth-century Baekje (Korean peninsula) blade that symbolizes Japanese-Korean exchange during the Asuka era——and the swords from the Tenpyo era (early Nara period) transmitted to Shōsōin (Nara). These blades display forms influenced by Chinese Tang-style straight swords, demonstrating that Japan from the Asuka through Nara periods employed continental-style straight swords as high-status ritual implements and weapons.

The Jinshin War (672), the greatest civil disturbance of the Asuka period, was a succession dispute fought between Prince Ōtomo (son of Emperor Tenji) and Emperor Tenmu (then known as Prince Ōama). This conflict was one of the largest military campaigns in Japanese history, with vast numbers of swords, bows, spears, and other weapons mobilized. Emperor Tenmu, victorious in the Jinshin War, hastened the establishment of the ritsuryo system and strengthened the veneration of the "Three Sacred Treasures"——mirror, jewel, and sword——as symbols of the emperor's absolute authority. In particular, the establishment of the practice of enshrining the Kusanagi-no-Tsurugi at Atsuta Shrine (Nagoya) became the starting point of Japan's distinctive "deification of the sword" culture, placing the sword at the very center of imperial authority.

From the late Asuka through the early Nara period, iron-smelting technology advanced dramatically. The nascent form of "tatara"——Japan's distinctive method of refining iron sand in furnaces——began to be confirmed, establishing the technical foundation that would enable the production of tamahagane (jewel-steel), the material of Japanese swords. The accumulation of this technology provided the fundamental condition that enabled the revolutionary evolution of Japanese swords in the late Heian period. The Asuka period thus occupies the position of the direct prehistory of Japanese swords, serving as the starting point for all development of Japanese sword culture.