Based on Okuroku-gun County, Mutsu Province (Inland area of Iwate Prefecture), he fought together with his father Yoritoki and his elder brother Sadato against MINAMOTO no Yoriyoshi (Zen kunen no eki).
陸奥国奥六郡（岩手県内陸部）を基盤とし、父・頼時、兄・貞任とともに源頼義と戦う（前九年の役）。