Earlier quoted context omitted.
I'm not convinced that language is actually such an essential aspect. Cultural similarity seems like a much bigger one. For example, I've seen Indians with great English struggle a lot more to fit in and acclimate than French students with poor English but more shared cultural touchstones. As an American, I've found it to be much easier to make friends with Europeans than with students from non-Western cultures—even…
If that were the case, then you should see Chinese international students hanging out with Japanese and Koreans. But from what I've seen, the various East Asian groups don't interact much. And each group speaks their own native language.
If it were the language barrier that was the issue then actually between Chinese and Japanese students while the spoken language is very different, they can sort of communicate between each other via writing.