Generally speaking, these provinces were eventually incorporated into Chinese territory in the Ming and Qing Dynasties. Because of the short time, the centripetal force and cohesion of the nation are naturally weaker.
Generally speaking, border provinces are inhabited by ethnic minorities, who have their own history, language and culture. How to deal with the relationship with them directly affects the stability of the region.
No matter what the problem is, it is still a human problem in the final analysis. Grasping "people" to write this paper. We should respect the habits of people with different cultural backgrounds, unite with the majority and crack down on a few separatists with ulterior motives.
That's basically it.
Personal opinion, for reference only.