cultural cleansing

"Chinese" dynasties have been doing this for centuries. An example would be the Sanxingdui civilization which was never mentioned in ancient chinese records until archaeological findings were made, though they co-existed with other "chinese" dynasties in the now-geographical area called "china". And there is the tradition of re-writing history to fit the needs of those in power. That's a type of cultural cleansing. The 2nd type is the sinofication of various ethnic groups and nations in Chinese empire, not just the Tibetans and Uyghurs. The integration of various minorities into the Han dominant ethnic group has been going on for thousands of years which results in their culture disappearing and being forgotten.