One of the earliest historical records of Japan suggests that by the late third or early fourth century a powerful warrior clan or group of clans living in the Yamato basin, an extremely rich and fertile plain in central Honshu, had subdued chieftains living in other parts of the country by a series of bloody wars. As a result of this conquest, the defeated chieftains acknowledge the hegemony of the chieftain of the Yamato clan.

Basic to the innovations of the seventh and early eighth centuries was a new concept of the ruler. The reformers borrowed the Chinese notion of an absolute monarch whose authority transcended the ties of kinship. He was to rule with the aid of wise and able ministers who would be appointed at his will and who would place loyalty and service to him above their own selfish interests.