I don't usually blog about politics, but as both a Buddhist with a deep appreciation for the Vajrayana and its syncretic Tibetan forms (Buddhism, like most religions, tends to absorb bits of other religions when it goes somewhere new; the Taoist and folk religion influence on Chan and Theravada influence on Thien are good examples of this), and as a Marxist who critically supports the Communist Party of China (some would call me a Dengist and think that's an insult), I've thought a lot about the political and religious situation in Tibet.
If you watch any documentary that has anything to do with Tibetan Buddhism, and it was produced anywhere other than in China, you're likely to be inundated with political posturing whether you realize it or not (Sinophobia is so ingrained in Western, and especially American, culture, that we frequently don't even realize that we're hearing racist and imperialist propaganda when it comes to China!). As far as I can tell, the people putting this stuff out there fall into two camps: blatantly anti-Communist and/or anti-Chinese State-department fans and/or racists who see the Dalai Lama and Tibet as a tool they can use to demonize the PRC or CPC, and those who are well-meaning but uneducated and not capable of critical thinking on a complex subject like the history of Tibet.
Tibet is complicated, and anyone uncritically supporting (including unwittingly) the so-called government-in-exile or the Communist Party of China's history in Tibet should really take a deeper look. I'll address both viewpoints.
The common perception of pre-Communist Tibet in the global north is of an idyllic, highly religious, peaceful society. This is a fabrication. Tibet was a theocratic dictatorship (I don't often use the word 'dictatorship', since in America, everyone we don't like is a dictator and everyone we do like is a benevolent leader, but this case warrants it) for much of its history, and until the communists reclaimed the region, was extremely poor (it's still poor, but less extremely) and essentially a feudal society, with serfs (some media will say slaves). Tibet was not like Bhutan is now, with a state religion and a monarchy but a largely happy and productive society. Think something more like the Taliban. The period between 1912 and 1950 was not a happy time for the average Tibetan under the theocratic absolute monarchy of the Gelug sect.
There is also a common misunderstanding about Tibetan Buddhism, namely that the Dalai Lama represents all Buddhists in Tibet. It's true that the Gelug sect was predominant since the time of the 5th Dalai Lama (17th century), but it is just one of four major Buddhist traditions (and there are other smaller sects besides). The Dalai Lama represents the Gelug tradition, which held political power for roughly three centuries, of which two centuries were actually under Qing rule, which brings me to the next point.
The fact that Tibet was only (de facto) independent in recent centuries for a few decades is almost always completely conveniently ignored. It was considered a part of the Qing Dynasty since the early 1700s, and retaken by China in 1950. Before Qing, Tibet was independent for roughly four centuries, and before that it was under the Yuan. Going back to before the 10th century the history is equally mixed. I'll address whether that's actually a justification for Chinese governance later.
Tibet is also an extremely poor region, and that factors heavily into how the CPC works with it. The Tibet Autonomous Region has 90% of its government costs paid for by the central government, and Tibet is exempt from paying taxes. China's crusade to end absolute poverty succeeded in October 2020. Tibet is still poor, but by sending teams to improve infrastructure and education, utilities, internet connectivity, and develop agricultural, commerce, and manufacturing industries, the CPC has worked hard to raise the average net income per person from roughly $220 to $1400 in four years in a sustainable way. That's not a lot of money, but it's a lot more than it was.
On the myth of cultural genocide or "Sinicization": that is largely a myth, just as it is in the case of Xinjiang. Tibet is roughly 90% ethnically Tibetan, and culturally still very much Tibet. The primary point most people make about this is that photos of the Dalai Lama were banned for a period and political (and religious) groups supporting him and the Central Tibetan Administration (the government in exile) have been repressed. Think about this in generic terms to bypass your internalized Sinophobia: If a government knows that there are groups actively supporting an organization that wants to overthrow part of your government, and that organization is partially supported and funded by other governments that are active enemies of your government who are known for a long history of staging coups and invasions far outside of its borders, is it reasonable to try to weed that out? Once you take out words like "China" and "Tibet", it probably seems pretty reasonable, even to Americans.
The last point I'll make here is that the government in exile and ant-Communist activity in Tibet were and likely still are heavily backed, funded, and trained, by the CIA, which is not known for spreading democracy and doing good deeds. The CIA overthrows democracies and destroys nations for capital and political gains. It's not the kind of organization you want on your side.
All that said, China is not necessarily in the right. This is a complicated subject and can't be reduced to "The Dalai Lama had slaves so China did the right thing".
The fact that Tibet has not been a truly independent state for more than 40 years in a long, long time, to me, is not actually all that important. Let's apply the same logic to the United States (with the obvious caveat that this is not an equal comparison, since the United States is a settler-colonial empire initially ruled by slaver landowners and now ruled by billionaires through their millionaire political pawns in both major parties, and also China didn't kill tens of millions of Tibetans....), and see how that works out. The indigenous peoples of the United States might have some opinions about whether having been occupied for centuries by Europeans is actually justification for continuing occupation. The same could be said about less brutal and oppressive empires than the US.
China's re-taking of Tibet, whether justified or not, was not not done well. In hindsight it could be seen as a liberation, but, like the Great Leap Forward and Cultural Revolution, there were many many mistakes made, some of them disastrous. That shouldn't be a point of debate among Marxists, even Maoists, because Marxism is not about dogma and leader-worship, it's about careful analysis. The annexation and effects of the Cultural Revolution in particular were unduly destructive of life, culture, and history. Important religious sites were destroyed. It didn't have to be that way. (If you're a Marxist who loves the "opium of the people" quote and uses that to justify some country or another's religious oppression, I challenge you to read the entire quote, in context, from the Critique of Hegel's Philosophy of Right, while keeping in mind that opium was seen largely as a painkiller and nothing more in the early 1800s in Europe. The problem with religion from a Marxist standpoint is organized religion as a political tool of capital, not religion in and of itself.)
I'm not Chinese, and I'm not Tibetan either, so my personal opinion isn't worth anything. If there was a movement for an independent Tibet that wasn't backed by imperialist nations to try to win political points against China and restore the theocratic rule of one of four major sects of Tibetan Buddhism, that might be an idea worth considering. There isn't, and even the current Dalai Lama no longer calls for something like that, so it's really a moot point (or would be, if the CIA and their Hollywood stooge mouthpieces would let it go). Right now, in 2020, it makes sense to support what the CPC is doing in Tibet, despite their mixed history for the first thirty or so years in Tibet.
Taking a hardline stance either way shows a lack of critical thinking, and is especially prevalent among Maoist types and pro-US-empire "Buddhists". That's not Marxism, it's also not the Middle Way. I hope this little post helped bring you some clarity on the Tibet issue.