This article in The Washington Post about Iraqis of African descent is fascinating. Recently I've been reading books about the Brazilian "racial democracy," and some of the quotes from Afro-Iraqis are exactly the same as Afro-Brazilians, they often de-emphasize their blackness and look to their commonalities with the general society, all the while being victims of racism from the lighter majority.

Though the presence of blacks in the Arab world is well known, their existence in India is not. The Muslim rulers of India brought black slaves with their armies to rule over the subcontinent, though several times the slaves rebelled and took power into their own hands, and black military leaders become de facto rulers. The Siddi people of India are the descendents of black Africans.

Update:
From Extensive Female-Mediated Gene Flow from Sub-Saharan Africa into Near Eastern Arab Populations from The American Journal of Human Genetics:

The mtDNAs of sub-Saharan origin that are present in Near Eastern populations show a striking phylogeographic pattern. They are virtually restricted to Arab populations, occurring at 35% in the Yemen Hadramawt and 10-15% in other Arab populations. They are absent or almost so from Turks, Armenians, Azeris, Georgians, and Near Eastern Jews and present at lower levels in Turkish Kurds. In Europe, they are detected at appreciable levels only in regions which experienced Arab rule during the medieval period. This pattern suggests that most female gene flow from sub-Saharan Africa into the Near East probably took place relatively recently, within the last 2,500 years. Y-chromosome data indicate that recent male gene flow was substantially less. This appears to be the case even for the Yemen, where more than a third of mtDNAs derive from Africa.

I suggest people read the full text, as it is available free.