From the ninth to the early 20th century, probably as many black Africans were forcibly taken across the Sahara, up the Nile valley, and across the Red Sea, as were transported across the Atlantic in a much shorter period. This work provides an introduction to this other slave trade.
Very important book examining the enslavement of black Africans in the Muslim world. Also has some translations of important Muslim texts dealing with the issue of slavery in Islam
This is a compilation of articles by Troutt Powell and Hunwick that offers valuable insight into Islamicate slavery. The title feels a bit misleading, though, because while the book does cover North African countries near the Mediterranean such as Algeria, Morocco, Tunisia, and Egypt, it also addresses Nigeria, present-day Sudan, Mali, and Chad. The book is excellent for the sheer volume of articles it includes (some of which would be difficult to find in translation) and for the care taken to clarify this neglected topic.