The Tibetan, Xinjiang and the Mongolian issues requires one to understand the Han culture.
Tibet, Xinjaing, The Min Basin and the Mongolian or Manchurian cannot be assimilated in China because of the Han culture.
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The problem will continue.
Han culturism differentiates between the culture of the Han, the inner people (nei ren) and the barbarians, the outer people (wai ren). This concept is a hand me down from the time of the Shang Dynasty, who political centre was located North of the Yellow River.
The Chinese differentiate between raw barbarians (shengfan) or the unassimilated people and the “cooked barbarians” (shufan) or those who were assimilated and yet were not the Han people e.g. the Han Chinese separated the ‘cooked’ Li of the coast of Hainan from the ‘uncooked’ Li of the central forest.
Barbarians were given generic names in the Chinese classics and histories: the Yi barbarians to the East, the Man to the South, Rong to the West and Di to the North.
Until the 1930s, the names of the outgroups (wai ren) were commonly written in characters with the animal radical: the Di, a northern tribe were linked to the dog; the Man and Min of the South were characterised with reptiles; the Qiangs were written with a sheep radical. This reflected the Han Chinese conviction that civilisation and culture were linked with humanity; alien groups living outside the pale of Han society were regarded as inhuman savages.
The custom of sharply distinguishing between the inner and outer people went along with the calling China the Middle Kingdom (zhong guo) , which began by ruling the Central plain (zhongyang) in North China. Rather than using outright military conquest, the theory of ‘using the Chinese ways to transform the barbarians (yongxiabianyi)’ was promulgated. By cultural absorption or racial integration through intermarriage, a barbarian could become a Han Chinese (Hanhua).