This was clearly known because a suggestion of kansenji (a government edict) against the complaint of Guji (chief of those who serves a shrine, controls festivals and general affairs) of Ise no Okami (Great God of Ise, aka Amaterasu Omikami) (in Tenyo-ki (documents on the disturbance in the Oba no mikuriya estate)) was discovered as a haimonjo (an old document which was written on the other side of a piece of used paper) of a kuge's dairy (court noble) at the time of 'The disturbance in Oba no mikuriya estate' in which it was attacked by MINAMOTO no Yoshitomo (father of MINAMOTO no Yoritomo) who was the third generation of Yoshiie 140 years after that.
このことが正確に知られるのは、それから140年後に義家から3代目の、源義朝（源頼朝の父）に攻めこまれるという「大庭御厨の濫妨」事件があり、そのときの伊勢大神宮司の訴状に対する官宣旨案（天養記）が公家の日記の背文書として発見されたからである。