[fiblye]

>Contrast Europe which has seen vast shifts in control, and utter replacements or eradication of local culture or tribes multiple times, going to prehistoric times, to the present (past century certainly, past few decades quite arguably). There have been very few constant borders or identities, certainly not on the scale of China.

Except you wouldn't contrast that. Those same events have happened in the region of China on the same scale as continental Europe as a whole. Entire societies have risen, conquered lands, and vanished.

The Manchu are the most notable example for coming in from the Northeast and conquering China. They had their own unique culture and language. Native speakers of their language are now countable on one hand.

The Tangut are another interesting example. They had a very unique culture and writing system unlike anything else and had their own empire in the middle of China. They were wiped out/eventually absorbed by Mongols and were completely forgotten for centuries until their writings were recently rediscovered.

Written Chinese today is an evolution of only one of the many, many cultures that formed what China is today. Even Japanese people can read classic Chinese texts with just a little practice, but they're definitely a separate society and always have been.

You could also argue western European cultures are all just Rome since they retain parts of the Latin language and writing system and can make out some words if they squint enough.