The Former Nine Years' War, waged by Minamoto Yoriyoshi (995–1082) against Abe Yoritoki (?–1057) and his son Sadatō (1019–1062), was the longest single conflict of the Heian (794–1180) period. The exploits of Yoriyoshi and his son Yoshiie (1041–1108) in this and the subsequent Latter Three Year's War of 1083–1087 helped forge the martial reputation of the Seiwa Genji line that founded the Kamakura shogunate, Japan's first warrior regime, a – century later.