Please don't spread nonsense.
"The online and print cultural materials of the Confucius Institute present a vision of[1] https://www.dw.com/en/why-is-the-us-targeting-chinas-confuci... [2] http://d-scholarship.pitt.edu/27901/1/The_Confucius_Institut...
"'Sinicization' - the thesis that all of the non-Han peoples who have entered the Chinese realm have eventually been assimilated into the Chinese culture--is a twentieth-century Han nationalist interpretation of China's past."In the other link I posted from professor Evelyn Rawski of U of Pittsburg, she explained that the last Chinese dynasty was the Qing who were ethnically Manchu. The Qing saw themselves as ruling five peoples, of which China was the most important. The Qing ruled China, Manchuria, Mongolia, Uighurs, and Tibet. When the Qing collapsed, Chinese nationalists, although they detested the Qing who were foreign conquerors, wanted to lay claim to all the territory the Qing ruled. I would do the same thing. But they used this strange construction of "Han Nationalism" and claimed that all the territory was really Han because the Qing was really Han. This is where the 5000 years of unbroken history propaganda comes from. Professor Rawski explains if you read the official Qing records which is in written in Manchu, the Qing did not "sinicize" or adopt Han culture. The Chinese liked to think they did but that is simply not true.
An interesting side note is that this bizarre cultural legitimacy argument cuts both ways. A few years ago, a Korean professor made the argument if you follow this line of thinking... you can argue that China really belongs to Korea. The founder of the Liao dynasty which once ruled Northern China was ethnically Khitan or "Qi Dan" in mandarin. The Khitan lands bordered Korea. There is some obscure record that conflates or can be construed that Yelu Abaoji is Korean... therefore China is really Korean. Bizarre. I don't remember the Korean professor's name but it caused a ruckus at the time.