I'll try to piece it together in a more coherent manner... I'm not too confident since I'm more fluent in 'crazy' than 'drooling idiot'
Ain't never been much melting
Let's see. He's either refering to race or culture, and quietly implying that visual differences made people instinctively refuse to associate in a meaningful way because it would 'weaken them as a people' or some bullshit.
A bunch of Europeans from similar cultures who looked sort of alike blended together to a fair degree
I guess he's refering to early political alliances and empires. He thinks the only reason they were able to interact, co-operate, and form greater political and military bodies is because they weren't grossed out too much by the foreigners' skin.
The other groups not so much
I think he's saying no brown people were allowed or acknowledged in white lands and no white people in the asian 'hood. The Brits and the early Chinese Dynasties didn't particularly get along, nor did they get on well with the Spaniards. I think we all know what happened with the Africans, Native Americans, and every South American civilitation upon contact. He's saying it was totally race related and not an issue of power-seekers seeking power.
Only groups mixing much across racial lines are at the bottom as a rule and it doesn't involve marriage
He's implying that only the lowest levels of civilized society: Trash, scum, peasants, and the irresponsible go for fuckbuddies of a different race and never do so for a serious commitment. He's a dipshit.
Exception... white boys... oriental chicks... some are fine too
He's saying white men are going for Asian women due to the cultural bent towards submission to their husbands. A trait craved by 'oldschool' (authoritarian asshole) Christians. He's saying he understands that reason and doesn't find some girls too hard on they eyes himself.
And since it's pretty much required for anyone with working eyes and hormones to say: Halle Berry = HOT! My father gave me some sage advice as a lad. Considering all the hot chicks in the world discrimination doesn't make a whole lot of sense, now does it?