I may have mentioned this source before, but a good source of more material is John Azumah Adembillah's book, The Legacy of Arab Islam in Africa.

Comparison: over 350 years, 15 million Africans were put on slave ships; 11 million reached the Americas. Over fourteen centuries, the trans-Sahara trade brought 18 million to the Arab slave markets--but left up to 120 million dead in the desert. And it might still be going on under the law's radar. Also, google the Zanj uprising.

You're most welcome, and with your permission, may I call you 'sister'?