I mean, Tibet was conquered by Chinese dynasties a few times in the past dozen centuries and so it’s been a part of the dominant one on and off over those years, but so have many other parts of China, such as the Taklamakan basin and Sichuan basin as well as their respective surrounding mountain ranges, Mongolia, Eastern Siberia, Yunnan (which used to be the independant kingdom of Dali). That doesnt make Tibet colonized, though. Being conquered does not make you colonized. Colonization implies resource extraction, underdevelopment, replacement of the native population, etc. Being a different ethnicity or belonging to a different cultural region also doesn’t cut it, as China is and has always been multiethnic and multicultural, as have been literally most if not all States from the dawn of civilization itself to basically the 19th century when the romantic ideal of the nation-state pushed European countries to unify their citizens under a single identity linguistic, cultural and ethnic identity, something China hasn’t done.

Edit: Oh yeah, and Communist China having ‘conquered’ Tibet is kind of a huge stretch. Tibet was part of the Qing Dynasty and only became an independant, theocratic, feudal country because of British support. When the Communists tookTibet, the Tibetan serfs thanked them as liberators, not as conquerors. Really, only the Monastic land-owning class was angry about it and fled the area a decade later, not because of any real persecution of the Tibetan people, but because they couldnt stand not being the rulers of the country anymore, much like Cuban gusanos.

Mao took away their serfs!

The history is somewhat complex and there had been times during which Tibet was an empire up until the 9th century after which it splintered, was then part of different Mongol and Chinese dynasties and at times a vessel state and semi autonomous in certain ways. To say the PRC colonized Tibet in 1950 is certainly wrong though, and today Tibet is one of 5 autonomous regions in China which grants it certain autonomy over particular internal matters. Tibet is also 90% ethnic Tibetans and 80% Buddhist.

Pre-1950s Tibet was a land of theocracy and feudalism. It was not a nation-state. When the communists liberated the serfs, they were welcomed with open arms by everyone on the plateau apart from the monastic elite. From then on, the multiethnic multicultural state of China would protect the language and culture of Tibet. The right of ethnic minorities to use and develop their own language and culture is written in the Chinese constitution and has been expanded at least 4 different times during the history of China 2002 being the latest I know of, 90% of Tibetans can speak Tibetan, hundreds of millions of dollars have been put into the upkeep of Tibetan cultural sites, such as almost 100 million into the Potala Palace alone, the 160 volume Tripitika was published by the Communists.