I don't doubt the dispute about whether it should be a part of India or China is real. But currently it is a part of India. Maybe China has legitimate claims. Maybe it doesn't. That's what I took your "should" to mean.
What's different about Tibet? China claims Tibet is a legitimate part of its territory, but others claim that China is an illegal occupier. However, at least for now, Tibet is a part of China.
What's different about Tibet? China claims Tibet is a legitimate part of its territory, but others claim that China is an illegal occupier. However, at least for now, Tibet is a part of China.