Idk much about Tibet & China, & it's such a contentious/propagandized issue I've been weary about to what to read about it. Luckily Michael Parenti wrote a short, fair, well cited essay on it that I just found linked in some Guardian article.

http://www.michaelparenti.org/Tibet.html 

I've heard people call Parenti a tankie but I've always found him incredibly nuanced. Just in case anyone is apprehensive about Parenti's ideology making the information unreliable, this is how he ends the article.