Swords of the Heian Period

The Heian period (794–1185) is the era that contains the most fundamental turning point in the history of the Japanese sword. Over roughly 400 years, the straight swords (chokutō) introduced from the continent evolved into curved swords (wantō) with a distinctive curvature, establishing the silhouette we now recognize as the nihontō (Japanese sword). This transformation of form was not merely a change in shape. It was a historical change inseparably bound up with the development of Japan's warrior culture, aesthetic sensibility, and spirituality.

In the early Heian period (around 794–900), swords were a continuation of the straight-sword culture that had continued from the Nara period. Ritsuryō-system military officials carried straight swords, and the imperial court produced and managed swords through an official weapons-manufacturing body called the Zōheishi (Tsuwamono-tsukuri-no-tsukasa). At this stage, swords were tools managed as part of the bureaucratic system, and the spiritual and aesthetic meanings that the later warrior culture would bestow on them had not yet matured.

In the mid-Heian period (around 900–1050), a decisive turning point occurred: the curved tachi, optimized for the combat style of mounted warriors (kiba musha), appeared. The tactical superiority of curved swords over straight ones was clear. Drawing quickly from the scabbard while on horseback required curvature, and in downward cutting motions too, the curve made the trajectory of the cut an arc, so the blade more easily bit into the opponent's body. The curvature born of this engineering necessity also realized an aesthetic silhouette at the same time, and it became a core element of the beauty of the Japanese sword.

Among the smiths representative of this period is Sanjō Munechika of Yamashiro (Kyoto). Munechika is known as the maker of the Tenka Goken 'Mikazuki Munechika' (currently in the collection of the Tokyo National Museum; National Treasure), and is positioned as the pinnacle of Heian-period swordsmiths. Mikazuki Munechika is a masterpiece with a gentle, elegant form. Within the blade, it displays a distinctive appearance called 'mikazuki-gata uchinoke' (crescent-shaped uchinoke), and it embodies the ideal in which the aesthetic sense of the Heian nobility and the practicality of the warrior harmonize. Another master of the same era was Yasutsuna of Hōki (present-day Tottori Prefecture). His work 'Dōjigiri Yasutsuna' (likewise a National Treasure and one of the Tenka Goken) is renowned as a sacred blade linked to the legend of Minamoto no Yorimitsu slaying the drinking demon Shuten Dōji on Mount Ōe.

In the late Heian period (1050–1185), the social rise of the warrior class (mononofu, samurai) fundamentally changed sword culture. The decline of Fujiwara regency politics and the budding of a warrior government transformed the sword from a 'ceremonial implement of civil officials' into a 'symbol of the warrior's soul, pride, and identity.' Through the series of power seizures by the warrior class, namely the Hōgen Rebellion (1156), the Heiji Rebellion (1159), and the Genpei War (1180–1185), swords stood at the center of history as the direct means of warriors' political acts.

The Genpei War (Jishō–Juei War) was also a cultural event that defined the nature of the Japanese sword. The attachment to swords that the warriors show in the Heike Monogatari (the pride of possessing famed blades, the shame of letting go of a sword, and the courtesy of praising an enemy general's famous sword) is the literary crystallization of the 'warrior's view of the sword' completed in the late Heian period. The concept established in this period, that 'the sword is the warrior's soul,' came to run through the core of Japanese sword culture, all the way through the later shintō, shinshintō, and modern swords (gendaitō).