According to the Imperial decree relating to Senkokushisho issued for the purpose of compiling Shin-kokushi as well as "Seikyuki" (exemplary book on Heian rituals) and "Shingishiki" (New Procedures in Administration), compilation of official history was conducted once after the passage of several eras of emperors.
新国史編纂のために出された撰国史所関連の宣旨や『西宮記』『新儀式』などによれば、数代の天皇ごとに国史の編纂がなされた。