That's what they did to Tibet for example and they absolutely are an extreme ongoing threat to Taiwan
China doesn’t want US military bases on their side of the Himalayas. It remained an autonomous region until a bunch of clowns proposed putting US military assets there.
It has similarities to Taiwan which is de facto independent but claimed by PRC.
Tibet has 3 million people, most of who are subsistence farmers or nomadic herders. Comparisons with Taiwan are a bit much.
I get that the Dali Lama is a really nice guy, but even he admits no one in Tibet gives a shit about him and becoming a feudal lord via picking objects as a child is a bit nuts.