Since around the end of the fifth century, influence of the Yamato (ancient Japanese) sovereignty gradually penetrated, but it was an area which the ritsuryo system (a system of centralized government based on the ritsuryo code) could not cover even after the enforcement of the Taiho Ritsuryo (Taiho Code).
5世紀末ごろから徐々に大和王権の影響が浸透していたが、大宝律令が施行された時点でも依然として律令制的支配の及ばない地域だった。