There are differences in contents between the imperial collections of the history books "Nihon Shoki," which described the process of unifying the country of "Japan," and "Zoku Nihonshi," which dealt with the history of the country after its formation.
“日本”という国家が形成されていく過程を描いた『日本書紀』とその国家が形成された後の歩みを描いた『続日本史』以後の勅撰国史ではその内容に違いが生じてくる。