This is supported by the family document of Tanaka, who was a Shinto priest of Iwashimizu Hachiman-gu Shrine, describing that the Imperial instruction of 1046, which was dedicated to Homutarama no misasagi (Mausoleum of Emperor Ojin) by MINAMOTO no Yorinobu, explicitly described that 'the ancestors are Shinbochi, Tsunemoto, Imperial Prince Motohira, Emperor Yozei, and Emperor Seiwa, from newest to oldest.'
石清水八幡宮祠官田中家文書の中に源頼信が誉田山陵（応神天皇陵）に納めたと称する永承元年告文に「先人新発、其先経基、其先元平親王、其先陽成天皇、其先清和天皇」と明記してあることが根拠である。