It may be the religeon, but I don't think you will find many Arab women married Pakistani, or any of the many non-arab nationalities that follow Islam.
Bora Bora, But then not all Arabs are muslim either. I know plenty of Arabs married to non-arabs. It's when religion gets thrown into the equation, that's when it becomes a little bit more complicated.
Chocoholic , true.. many muslims who don't give much worth(or unconscious) to the scripture actually do marry people out of their communities. But when they pay attention to the advice of religion then they pick and choose who they marry even amongts each other. For those believers, white supremacy, richness or lineage doesn't play much role other than piousness first, which was also the practise of the prophet..