Nobuyori's branch of the Fujiwara clan had long controlled the provinces of Musashi and Hitachi through their fiefs there, and had a friendly relationship with MINAMOTO no Yoshitomo, who had strong ties to both provinces.
もともと信頼の一門は武蔵国・陸奥国を知行国としており、両国と深いつながりを持つ源義朝と連携していた。