According to the petition letter of Yoritoshi written in February 4, 1071, there was an incident that very atrocious persons including Sani (courtier without post) FUJIWARA no Motomichi who had his territory in southern part of Mutsu Province denied kanmotsu (tribute goods paid as taxes or tithes) and kuji (public duties) and bereaved the seal of province and the key to the provincial treasury during the conquest.
その間、延久2年（1070年）12月26日に記された頼俊の解状によれば、陸奥国南部に領地のあった散位藤原基通(散位)などの梟悪之者が官物や公事を拒否した上、国印と国倉の鍵を奪うという事件が発生した。