It was compiled by FUJIWARA no Shinzei as a history book that continued the legacy of Rikkokushi (the Six National Histories), upon the imperial order by the Retired Emperor Toba (1103-1156, reigned as an emperor: 1107-1123).
六国史後を継ぐ史書として、鳥羽上皇（1103年-1156年、天皇在位1107年-1123年）の命により、信西が編纂。