Islam's Black Slaves: A History of Africa's Other Black Diaspora

Unlike the millions of west Africans who were crammed on to coffin ships bound for plantations in the Americas, those dragged through the Sahara or down to the Indian ocean at Zanzibar were mostly women. Zanzibar was a black Belsen, a clearing house of shackled humanity, where the stench of death was masked by the cloves on which the island's Omani emirs built a great trading empire.

Without a nascent industrial complex to feed, many of the men were castrated for domestic service or drafted into slave armies that emptied the lands around the great lakes of their peoples. One in 10, by some estimates, survived the trek from the interior. Book Review