Another thing to keep in mind is that "tribalism" didn't become "racism" until around three or four hundred years ago, possibly even more recently (with the advent of Darwinism and stuff). During the Roman Empire, Roman citizens were the "tribe" and it didn't matter what your race or ethnicity was. Non-Roman citizens were the folks that got stomped on and abused and enslaved. During the Crusades, professed members of the Church were the "tribe" and as long as you were one of them or decided to become one of them, you were all good. Pagans and heathens were not members of the "tribe" and so they got the short end of the stick. During WWII members of the Nazi party were the "tribe" and anyone outside the party (especially fellow Germans) were targeted for subjugation and extermination.
Sorry, this was off the Warden topic, I just felt like I should chime in. When I read history books and stories, the mention of race is rare and people seem to be primarily concerned with "can we get along with these outsiders," regardless of where they come from and what they look like.