The monograph is dedicated to a little-studied period in the history of Japan - the era of middle Yamato (late IV - V centuries). Important events take place at this time. In ancient Japanese society, there were three classes and three estates inherent in any ancient society. The Yamato state, having established strong allied relations with the ancient Korean state of Baekje and the confederation of South Korean communities of Kai, begins to actively intervene in the military-political affairs of South Korea, fighting against the South Korean state of Silla and the North Korean state of Goguryeo. Yamato renews diplomatic ties with South Chinese dynasties.