Based on the account in the former "Gukansho," Yasuaki NAGAZUMI assumed that "Hogen Monogatari" came into existence before "Gukansho" was completed in 1220.
とくに前者の『愚管抄』の記述については、このことを根拠のひとつとして永積安明は『愚管抄』成立（1220年）以前に『保元物語』の誕生をみる。