Japanese Ō-yoroi Armor

Timeline

1. c. 1100–1185Kyoto · KyotoIn the late Heian period the samurai class grew, and mounted-archery tactics (yabusame, tsuioku) drove the standardization of the ō-yoroi: cuirass and large sode shoulder guards protected the front in the shooting posture, hiba-leaf-shaped kusazuri hung to protect the legs, and the back was relatively weak to reduce weight.
2. 1185–1220Kamakura · KamakuraThe Kamakura shogunate sustained samurai military service through on and hōkō, and the ō-yoroi became the standard heavy armor for gokenin campaigns and ceremonial occasions. The shogunate linked armor supply to fief rank through land surveys and military-service systems, and 12th–13th-century ō-yoroi production emphasized lacquering, cord coloring, and family-crest identification.
3. c. 1300–1400Japan · JapanWith the wars of the Nanboku-chō period and the rise of ashigaru infantry tactics, the cumbersome ō-yoroi was less agile in field battles and close combat than the dō-maru and haramaki; it gradually receded to a role as ceremonial and votive armor for high-ranking samurai, with surviving examples mostly preserved in shrines and museums.