To say that China's occupation of Tibet is legitimate is to deny the importance of past efforts of peoples to establish their own nations or fight for their rights. What would the world be today without the American Revolution, the civil rights movement, the independence movements of former colonial possessions like India, South America, and the Philippines, the abolition of apartheid, the abolition of slavery, the ideals of the French Revolution, Mahatma Gandhi, Martin Luther King?
By insisting that Tibet is rightfully theirs, the Chinese are bringing history back to the dark age of manifest destiny, when nations with enough military and economic might could easily declare any part of the world as their own.
Colonial masters have always been freaks. While they advance in wealth and technology, their ideas--about the colonized, about the "Other"--regress towards some kind of pre-enlightened ignorance. We all know what happened to colonial masters. Perhaps China seeks to experience that firsthand. We must give it to them.