CCP bots try to manufacture their own history but classical Chinese literature clearly separates sedentary Han Chinese people from the nomadic tribes like Mongols who were considered uncivilized.

There was prohibition on immigration of Han Chinese into Manchuria by the Qing dynasty who wanted to protect their ancestral homeland.

The present Han Chinese population moved there only in the 18th century.

Inner Mongolia and Manchuria became Han Chinese majority in 18th century when greedy Yuan Mongol princes started giving lands to settlers to extract loans.

Also, Inner Manchuria was sparsely populated and the Russians were about to annex it like Outer Manchuria.

Yunnan became Han Chinese majority during the Yuan rule because of mass migration.

Same for Guangxi, while Guangdong's Chinese are a result of miscegenation and Sinicization.

Taiwan became Chinese majority only around late 18th century under Qing rule.

Dzungaria was first depopulated of its Oirat population and then resettled with Han immigrants.

If Vietnam stayed under Chinese control, it's likely they would've met the same fate as Yunnan or Guangxi.