Since AD 220, three countries, namely Wei, Shu and Wu, have been established in Chinese history. It was divided into three parts, which were fragmented, dominated and confronted each other, and basically covered all the territory of China at that time, except a few wild places. Therefore, historians often refer to this political situation as the period of Wei, Shu and Wu, in which the three kingdoms stood in the balance. Although the war of annexation continued, the rulers of the three countries paid more attention to the development of social production and the stability of social order in order to consolidate and develop their power. Compared with the chaotic situation of many warlords in the late Eastern Han Dynasty, it is much better. In fact, the tripartite confrontation between the three countries is a transitional stage of China's gradual reunification after more than ten years of destruction. The rulers of the Three Kingdoms adopted some political and economic measures in their own countries, such as Cao Cao's reclamation and the implementation of the Jiupin Zheng Zhi system. Zhuge Liang's strategy of "going west and going out, entering foreign enemies in the south, Sun Quan outside, politics inside"; Sun Wu's ruling policy of developing aristocratic families objectively played a beneficial role in the unification of the whole country, and their emergence and existence were reasonable.