It's still not really a skin color thing. It often looks like it's skin color people are discriminating against, but the underlying subconscious reason is that generally speaking, peoples of certain skin colors usually share similar values and behavioral traits. The key word here is "generally." Generally, white people are of European values and culture. Generally arabs are of middle eastern values and culture. Same principle is applied to blacks, asians, etc.... So when people discriminate because of a color, they are mostly jumping to the conclusion that the person of said color probably has the values, culture, and behaviors that their people are generally known to have. And 90% of the time, they would be correct with this assessment. Forcing a melting pot of peoples with varying cultures, religions, values, etc is proving to not be a good idea. Inevitably this will lead to social unrest, civil wars, paranoia, hatred, etc... A perfect world would be one where people of all cultural backgrounds (generally speaking (colors)) could have their own country, culture, politics, behaviors, etc. otherwise, you are starting to see the stress fractures that a melting pot causes, especially I the western nations.