Early Tenpei Ancient Swords and Nara Imperial Workshops

The years from Tenpei 13 to 20 (741–748) coincided with the political and cultural zenith of the Nara period in Japan. Under Emperor Shōmu's reign, the edict ordering the construction of provincial temples (kokubunji) was issued in 741, construction of the Shigaraki Palace began in 742, and in 743 the edict ordering the casting of the Great Buddha (Rushana-butsu) at Tōdaiji was issued — the most ambitious state-sponsored Buddhist project in all of ancient Japanese cultural history, pursued in rapid succession. This concentration of metalworking technology at a state scale had indirect effects on sword production. Nara's state workshops (government offices known as kanga kōbō) were bureaucratic production organizations responsible for manufacturing a wide range of metal goods from Buddhist implements and temple bells to weapons; within this system, the Hyōbushō (Ministry of Military Affairs) lineage of workshops was one of the principal sword-producing entities.

Swords of the Tenpei period belong to the earliest stratum of Japanese sword history — the era of the chokutō (straight sword), fundamentally distinct from the wantō (curved Japanese sword) that emerged in the Heian period and later. Tenpei-period blades are nearly linear in form, with cross-sections taking the form of shinogi-zukuri (ridgeline construction) or kataba (single-bevel). The kissaki (blade tip) shows transitional forms in this period: moving from the warabi-te (fiddlehead-shaped, curled inward) type to the simpler maruiri (rounded-tip) form. The iron material shows a mixture of domestic wa-tetsu (Japanese iron) and continental forging techniques, as the uniform Japanese tamahagane production method was not yet established — it would emerge in the subsequent Heian period. Tenpei-period swords thus bear strong continental influence in both material and technique, reflecting the impact of Tang-dynasty China and the Korean peninsula.

The Shōsōin treasure repository at Tōdaiji in Nara is the most important source of material evidence for Tenpei-period swords. This repository holds swords donated by Empress Kōmyō from Emperor Shōmu's personal effects in 756 (Tenpei Shōhō 8) — still preserved today. Among the Shōsōin's imperial treasures are several Nara-period swords and great swords, including the kinginzō no tachi (gold-and-silver-mounted great sword) and the hirao no tachi (flat-cord-mounted great sword). These objects possess unparalleled world significance as actual material evidence of Tenpei-period sword production technology and decorative style. The gold-work ornamentation of the kinginzō no tachi shows strong continental (Tang-style) influence, testifying that Japan's sword culture during the Nara period was in an active phase of absorbing continental cultural forms.

The warabi-te sword (warabi-te-tō) was a distinctive sword form used in northern Japan (Tōhoku and Hokkaidō regions) during and prior to the Tenpei period, characterized by a kissaki curled inward like a fiddlehead fern sprout. The warabi-te sword emerged from the fusion of indigenous Jōmon and Yayoi sword culture with continental iron-smelting technology, and has been discussed as a potential influence on the formation of the curved kissaki of the later wantō. The transition from straight to curved swords during and after the Tenpei period was gradual, and research into the curvature of warabi-te swords provides important physical evidence in the scholarly debate about the origins of the Japanese sword's distinctive sori (curve).

Sword production in Nara's state workshops was deeply integrated with the ritsuryo system of imperial-law bureaucracy. Under the jurisdiction of the Hyōbushō defined by the Taihō Code (701) and Yōrō Code (718), organized groups of craftsmen produced swords, armor, bows and arrows. These state artisans (kan'ei kōshō) were technicians under direct state administration — categorically different in character from the medieval sword-smiths (katana-kaji) of later centuries. The fundamental distinction between Tenpei-period sword production and later medieval sword culture is precisely this: Tenpei swords were not the autonomous creative work of individually named master smiths, but organized state production functioning as a component of imperial bureaucracy.