Ō-yoroi (Samurai Armor)

Timeline

1. 1000–1150Kinai (around Kyoto) · KinaiAs the samurai class rose in the late Heian period, mounted-archery tactics drove the combination of asymmetric large sleeves, haramaki, and star-shaped helmets into the basic form of ō-yoroi, serving the mounted combat needs of the aristocratic warrior houses.
2. c. 1180–1200Japan (Kinai-Kanto battlefields) · JapanDuring the Genpei War of 1180-1200, ō-yoroi was widely deployed in combat as the standard heavy armor of mounted-archery samurai of the Minamoto and Taira clans; armor-making and color-coding systems became standardized, becoming a visual symbol of warrior-house power.
3. c. 1200–1400Kamakura and throughout Japan · KantoAfter the Kamakura shogunate was established, infantry and group combat increased, and lighter armor such as dō-maru and haramaki gradually spread; ō-yoroi remained in use for ceremonies and high-ranking samurai, but gradually ceded its dominant combat role.