This is the general tone that China justifies the invasion: Tibet was feudal, people were slaves, we liberated them, now everybody is happy.
There had been many bad things going on in Tibet, but it does not mean you can just invade the country, destroy all forms of religion, put people in prisons, starve and kill your victims, grab the resources, make the life of Tibetans miserable, and pretend you are the great liberator - only because of superior military power.
Many witnesses of what happened in the 50s are till alive, some managed to escape to India. When you read their testimony[0] all arguments of China become bleak.
There had been many bad things going on in Tibet, but it does not mean you can just invade the country, destroy all forms of religion, put people in prisons, starve and kill your victims, grab the resources, make the life of Tibetans miserable, and pretend you are the great liberator - only because of superior military power.
Many witnesses of what happened in the 50s are till alive, some managed to escape to India. When you read their testimony[0] all arguments of China become bleak.
[0] https://www.amazon.com/Autobiography-Tibetan-Monk-Palden-Gya...