How sure are you about that? Most "white" people don't actually fully integrate to the culture, despite marrying and raising kids.
Take a look at this video about a Chinese villager with Russian ancestry: https://www.youtube.com/watch?v=2rS30IjG05c
He is completely culturally Chinese, although in a rural kind of way, in his speech and mannerisms. If you can read Chinese, the comments are very inclusive.
"Non-Asian" people have settled in China for hundreds of years, especially Arab traders who arrived through the silk road. Multiculturalism is not a foreign concept in China.