Part of that is how successful their colonization of Tibet has been ( https://en.wikipedia.org/wiki/Lhasa_(prefecture-level_city)#Ethnicity https://en.wikipedia

Part of that is how successful their colonization of Tibet has been ( https://en.wikipedia.org/wiki/Lhasa_(prefecture-level_city)#Ethnicity https://en.wikipedia.org/wiki/Lhasa_(prefecture-level_city)#... ), Han chinese making up 35% of the population as of 2000, other more modern estimates put it a ~66%. It's a lot harder to make the case for independence when there is a large Chinese minority, even harder if it becomes a majority.