So, let's take this question to Japan. Japan is known to be rather racist, in ways. Japan doesn't want a lot of immigrants, because they want to remain... God forbid, Japanese.
What if by some pressure they are forced to take on some Subsaharan Africans who have been displaced because of war. Subsaharan Africans from any state and Japanese are phenotypically and culturally very different, and genetically, enough. And frankly, some of what many call "racism" is a natural and healthy response. Japanese people, though there are within them different major groups of native people (Its a sliding scale everywhere, and perhaps different resolutions, but some 'types' mix with others more readily and easily), are a product of thousands of years of selective pressure and evolution. If they have a sense of pride in their identity, and have collective identity with their family and extended family and culture, and they wish to preserve that in light of a population and increasing population of outsiders, who only just recently in the last even 500 years have been introduced, and are not the same still... If a Japanese man or woman chooses to only want to be with their own relative kind, for self preservation, I know so many of your brains won't know what to do about it, and will just call it racist. "Why can't I have it too??" "Not fair!"
Go Japan.
I can't believe some people say they should let in massive immigrant populations because simply their economy and social security system won't be able to support them. Then change the fucking system. Don't just invite a third world people into your country to become "workers", and to reproduce at rates higher than your people, who the Marxist world will force by shaming and disrespect/tearing down of your unique separate identity to mix. And hey, here is a fresh boat!
Call me the devil. I don't care.
Now let's travel to the U.S. European Whites were 90+% of the population up until 1965, when immigration policy changed. Now, they are roughly 60% of the population. This is in a span of about 50-60 years, that we have experienced a change as such. It is only projected to change more, and as time passes, there will be less and less chance for any unique population, such as 'European Whites' who blend most readily with one another, to stay unique. In 200-300 years time the average person will be an admixture it's likely, and probably resemble less White than Non, and pressure to stay unique will be less in respects (maybe more, in others), because more will be mixed. It is completely natural to want to preserve what your general race has become, even if unconsciously in the form of bias. And in ways, 'nations' became strong because of their certain ability to wear a uniform. Teams know who is on the same team. Now we enter a different age- an insecure age. Unknown. And people are shamed for not following the rest off of the proverbial cliff (not to say it leads to death literally, but certainly it does).
I understand we are not so Black or White. You don't gotta tell me. I've got Native American in me, and I don't see any Native Americans around these parts (unless you count Mexican peoples or others, which, they are, but slightly differentdifferent than what many associate as such). Though different, it is similar.