Why did ancient China establish clan relations with some countries such as Korea instead of annexing them? Answer please full

" Zongfan". Refers to the clan vassals who were subdivided by the Son of Heaven. Because of its arching the royal family, as if a fence.

Ancient China's zongfan system is an integral part of the traditional Chinese political system, and to a certain extent conforms to the internal evolutionary laws of the ancient Chinese political system. Chinese diplomatic thought under the "clan system" is a contradiction in the pursuit of "peace" on the basis of the idea of "the center of China", which has gone through a development process from the norms of human interaction to the internal system of the state, and then to the rules of state-to-state interaction. The mother of contemporary Chinese diplomatic thought is the diplomatic thought embodied in the ancient "Zongfan Diplomacy", especially the concept of "peace***tong" and "harmony in the world", which not only rejects the concept of "Huaxia center", but also inherits and develops the diplomatic thought of "peace".

Conclusion: The fact that Korea and Vietnam, for example, became vassals of certain Chinese dynasties was a result of the strength of the specific central dynasties and of these local vassals at the time. It was also the influence of the will of the highest decision makers. The survival of these states was not an accidental factor, but a necessity for the integration of the various ethnic groups. In general it had to do with the dependence of the Chinese interior. North Korea and Vietnam are far away from China's ruling core, and at the same time are not as ethnically integrated as Tibet and Xinjiang. Religious, economic and cultural ties are weaker.

Reference: Liu Zaiqi, "Chinese Diplomatic Thought and Peace under the Zongfan System", Academic Exploration, 2011, 02.