I've seen it and heard of it numerous times with India and China. But not Korea, Japan, Pakistan, or other countries. I find this inexplicable.
I would be more surprised if it was anything but “India and China” in your observations, just due to raw volumes.
In contrast, I have only worked with a small handful of Australians.. they are too few and far between to plausibly form all-Australian teams. I have worked with far more Japanese, Korean and Pakistani coworkers; these nationalities have been heavily represented in the workplaces I have experience with yet I've never seen nor heard of a team where they were conspicuously over-represented.
Another thing: In my entire career I've never been on a team of only white people (of any nationality), nor to the best of my recollection have I ever seen a team larger than 4 or 5 that only had white people. Guestimating some rough numbers... if a company is 50% white and 15% Chinese and there are no ethnic biases present, what are the odds I would see numerous large all-Chinese teams but never a large all-white team? This sort of circumstance arising without bias seems deeply implausible.