As late as the 1960's there were restrictions on immigration from non-European countries and those were for very good reasons. Despite what idealists would like to believe - In fact, all men are NOT created equal. That's not a by-product of politics, religion or racism, it just is. There were many paths in human evolution. During the sifting process, some remained frozen in place and time, others went extinct, other branched into different environments and developed different traits. You can't take a bushman of the Kalahari, put him in a suit and expect him to design a cathedral or even develop a wheel. That sounds racist to our ears but that's an obvious fact. Some of it is education, opportunity, nutrition, institution...but only a sliver.
If we approached the problems associated with these populations from that perspective - instead of just spending trillions of dollars to find new ways to blame ourselves and assuage our guilt by letting them run amok it would be much more productive for everyone. It's science - like climate change.
Presently, look at what this anthropomorphic folly is getting people here, in Europe, Australia, Japan. Anywhere there is forced, politically motivated 'diversity', there is chaos, crime, corruption and carnage - The Four C's.