If lies can keep people feel happy, secured and united, I don't see the point to stop lying.
My grandfather has worked 15 years in Tibet and all I know is that he loved the soil and the people, and he was loved too. He has never mentioned the unhappy Tibetans, and I don't think he hid that part from me for politic reasons. I have been to the Inner Mongolia myself and I didn't feel any existence of hatred towards the Chinese people either. In fact they are now considering themselves Chinese, too. And yes, they are both parts of the People's Republic of China. It is what I was told, and also how they are recognized officially by the UN if I'm not mistaken.
No place is ought to belong to anyone, for eternity cannot be possessed by the creations of time. It is history that has led Tibet part of China for now, and it can very well be a land of somebody else's tomorrow. In the meantime, people live.