>vietnam vs China
Some of those groups hate the Chinese more then the Vietnamness (See Hmong). Others of them are basically statistically irrelevant (pop under 50,000). Most of them don't give a fuck but their lifestyle is more "Chinese" like if you could call it that (eg; not living on stiled house afraid of typhoon, and rather afraid of seasonal flooding and earthquakes).
It's a bit weird in that area, since it's not a hard cultural boundary like a mountain range and the cultural border isn't strictly a line. Think like the divide between Germany and interwar Czech/poland where there's a large group of inbetween, or better yet, Jugoslavia with less noticeable religious differences.
>turn muslims into bhuddist or athiest
the latter, the CPC doesn't encourage any religion aside from state sponsored cult of personality. Plus, the muslims lie anyways so they will just convert back. A Common paralance in Mandarin is "You can trust the food a muslim makes (since it is halal and not has MSG or gutter oil), but you can never trust anything they say".
Plus, it's fun converting certain muslims culturally by feeding them pork lol.
Manchus are technically pretty closely related to the "Han". In the Song dynasties, the northern Jurchen state adopted Chinese culture (but not language), and in the infamous Jingkang incident, took prisoner the majority of the Song imperial court and family. The Jurchens were then destroyed by the mongols, but the families lived on and traced their decent through the Jurchens and Song era Han.
It is noteworthy to note that historically they were considered non-Han because they were considered outsiders that had "missed out" on the 200- year era of the Ming (despite being nominally subordinated), and thus weren't as up to date on many things and started developing their own culture (A good example is that Manchu women the early Qing years were not afraid to talk to other men in private (A big nono in Han confucianisim), and the men didn't care (as much) about female virginity because how do you raise a child when its -20C by yourself back then with no monies?
. It was considered acceptable that if your cousin or brother's wife died that you could "marry" them to prevent them from being frozen to death. That most definitely is not acceptable by (neo) Confucian standards, a widow should commit suicide after raising their children was the norm.