This was my observation too. Actually you see this ethnic-based clustering with others too, but it's just that the Chinese stick out more cos yes, there's usually more of them in STEM subjects. They're also not afraid to openly converse in their own language, even in class projects!

Sometimes I think that locals can do more to interact with them. Their presence is also our opportunity to learn from them. There's a lot of prejudice (Chinese people cheat for example) which surprise surprise, if you mingle more, you'll realise it's as stupid as saying white people like to party all the time.

Ultimately we group together to feel safer. If you approach one with a friendly face, you're likely to be received with appreciation and intrigue. If not...well what exactly have you got to lose? Don't let bad experience shape your prejudice though.