Although the dynasty system is usually placed as having existed during the end of ancient times, it is also possible to place it during the early years of the middle age having a decentralized system and it is generally accepted as a transient period from the ancient period to the middle age (the expression 'Chuko' (literally, middle old) is used in the historical study of Japanese literature).
王朝国家体制期は、通常古代の末期に位置づけられるが、分権的な中世の萌芽期と位置づけることも可能であり、古代から中世への過渡期と理解されている（日本文学史研究においては「中古」という表現も用いられている）。