The bible devotes a whole chapter to marrying outside of ones culture. God said don't do it. As a matter of fact, He ordered the families split up where a man had married outside of his race or in that case it was culture. People have twisted the facts where they have placed too much emphasis on the physical differences. It was the cultural differences God was concerned with. When He ordered the families split up, He also ordered the men to provide the estranged wife and children with a home and their needs. But you are right, it was to preserve the purity of the culture. Its just like an Irish Catholic marrying an English Protestant. Same color, just different cultures. One would give up their culture to accomadate the other. That is what was behind God not wanting what He called mixed marriages. He knew people would be better off if the children learned about their true heritage but now cultures are so mixed, the ways of your people don't mean anything and I think sadly the knowledge of the kind of culture and people you came from is lost. It has nothing to do with one race being superior to another. The idea that races shouldn't mix because of physical differences or one race being superior to another is just a myth that man created and the real reason has been totally obscured and the way society thinks now, God would be a racist. I do think God made people different colors to make humanity diverse and to beautify His world and to make it easy for people to see the differences. But I think, too, that God was mostly concerned with the Jews remaining pure because whether people like it or not, they are God's chosen people. I think thats why they are so hated by the left.
Jewish rabbis today are very concerned about "marrying out" and are starting to discourage it more. Then there's the story of Phineas, who when a "mixed" couple (a Jew married to a gentile) appeared before him, killed them both -- from which charming episode the modern "Phineas priest" assassins take their names.
Then there's the story of Solomon and the Queen of Sheba. He married her, didn't he?
The phenomenon of "black Jews" goes back at least to the New Testament: remember how Philip encountered the man on the road who was coming down from Jerusalem, returning to his home in Ethiopia? The man was a treasury official appointed by Queen Kandaka (in the Greek spelling -- we recognize the name in its Latinized form, "Candace": bet Candy Bergen doesn't know she's named for a 2000-year-old Queen of Ethiopia). He was an Ethiopian Jew. They still have Ethiopian Jews. How'd that happen?