Race and color did matter in the Muslim world and they still do. However, the colourline is not exactly the same as that in pre-abolition America. I would say in the Muslim World it’s like the one-drop rule in reverse, as seen by so many African ethnic communities that are predominantly Muslim claiming Arab ancestry. As the majority of Muslim societies are patrilineal one’s mother’s ethnic origin doesn’t really count. Actually, sometimes slave women (not all of them Black) were preferred because they had no families or social ties to the communities they were enslaved in so there was a great deal of Muslims who rose to prominence whose mothers were Black slaves. This was true in the Pre-Islamic era as well (Note the famous story of warrior poet Antar ibn Shaddad). However, to totally ignore how these prejudices created oppressive and racist power structures within Muslim Societies in Africa is incomprehensible.