Jōkotō (Kofun–Nara Period)

The Arrival of Continental Ironworking

Iron manufacturing technology arrived in the Japanese archipelago from the Korean peninsula and the Chinese continent during the Yayoi period (3rd century BCE to 3rd century CE). The earliest iron objects were primarily agricultural and craft tools; swords are thought to have been introduced somewhat later. As the Kofun period (3rd–7th centuries) began, numerous straight swords and short blades appeared as burial goods in the great earthen tombs of regional chiefs, indicating that sword-forging skills were being mastered throughout the archipelago.

The swords of this era are collectively called jōkotō (ancient swords), a conventional term for distinguishing them from the later Japanese sword (the curved tachi). As straight-bladed forms, clear continuity with continental sword types is evident. The basic form is a straight sword without curvature, with edge and spine running parallel. Swords are classified by pommel type: ring-pommel swords (kantō-tachi), diamond-pommel swords (keitō-tachi), and single-phoenix-ring-pommel swords.

Characteristics and Technology of Kofun-Period Swords

The swords excavated from kofun include both ceremonial and burial pieces as well as functional weapons. Manufacturing technique improved over time, and metallurgical analysis has confirmed that quench-hardening technology was introduced around the 5th–6th centuries.

A representative example is the gold-inlaid iron sword excavated from the Inariyama Kofun in Gyōda, Saitama. A 115-character gold-inlay inscription is engraved on both sides, and the inscription recording "the year of Xin-Hai (471 CE)" is important historical evidence indicating the political power structures of the time. Finely crafted iron swords have also been recovered from the tombs of regional chiefs at various locations, such as the Higashida Ōtsuka Kofun in Sakurai, Nara Prefecture, and it is suggested that skilled swordmakers from the Korean peninsula who came to the archipelago in the 5th century greatly advanced local forging technology.

The Shichishito — a sword with six branches preserved at Isonokami Shrine in Nara — is traditionally said to have been presented to the Yamato king by the kingdom of Baekje (4th century). Manufactured not as a practical tool but as a ritual implement, this sword is among the most important sources of evidence for both the political relationship between Japan and the Korean peninsula at that time and the advanced forging technology of the era.

The Shōsōin and Swords of the Asuka and Nara Periods

From the Asuka period (593–710) to the Nara period (710–794), sword culture underwent significant transformation alongside the formation of the ritsuryo (imperial code) state. The imperial court, which actively absorbed Tang Chinese culture, enthusiastically produced ceremonial swords with magnificent metalwork on their hilts and scabbards.

Swords associated with Emperor Shōmu are preserved in the Shōsōin repository attached to Tōdaiji Temple in Nara. Swords from the Nara period such as the "Kingindenso Karatachi" (gold-silver-inlaid Tang-style long sword) and the "Kingindenso Katana," adorned abundantly with gold, silver, shell, and gemstones on hilt and scabbard, are highly regarded worldwide as artworks representing the pinnacle of court culture of that time. These sword blades retain the straight-sword form, yet their forging technique and blade geometry had reached a stage that would serve as a bridge to the Japanese sword of later periods.

The Warabite-tō and the Transition to Curved Blades

The transition from jōkotō (ancient swords) to the Japanese sword (curved tachi) was not abrupt but occurred gradually over approximately two centuries from the 8th to the 10th century. One sword type that bridged this transition was the "warabite-tō" (bracken-fern-hilt sword).

The warabite-tō was used by the Emishi, the indigenous people of northern Japan (Mutsu and Dewa provinces), and is characterized by a distinctive pommel that curls inward like the emerging frond of a bracken fern. Specimens have been excavated from sites throughout the Tohoku region, and examples have also been found in the vicinity of Sendai. Academically important as a transitional form between straight and curved swords, the warabite-tō is fascinating evidence of the possibility that the sword culture of the Tohoku region contributed to the birth of the Japanese sword. The incipient curvature visible in the warabite-tō is a revolutionary characteristic that leads to the curved form of the later Japanese sword.

The Modern Significance of Jōkotō

Jōkotō occupy a special category that does not circulate in the modern Japanese sword collector market, and their study stands at the intersection of archaeology, cultural property science, and sword history. However, knowledge of jōkotō is indispensable for a deeper understanding of the historical miracle that was the birth of the Japanese sword.

Why did the Japanese sword come to possess such a distinctive form and manufacturing method? — Part of the answer lies hidden in the era of jōkotō, where multiple factors overlapped: the introduction of technology from the continent, the trial and error of craftspeople at various locations, the demands of actual combat, and the aesthetic vision of the imperial court. Through studying sword history, we today can also experience anew the sense of cultural continuity and transformative wonder that the samurai must have felt upon encountering the treasured swords of the Shōsōin.