I've used Manning and it worked. I also covered ancient system of
African slavery. Nile valley stuff. I think it was a positive
element of the course.
Taylor is fine. I've been using that for a while in my course on
Ancient Nile societies. Also the Museum Guide by Joyce Haye/
Haynes is good and if you are near Boston you should take students to
see the collection on Nubia there. We had two fantastic Nubian
Institues at the MFA in the summers of 1993 and 1994. The Nubia
exhbit has been on the road for a while and will next be at the
Smithsonian. Check it out.
You might also try some of the UNESCO African history/U Calif.volumes.
They are great sources and now in paperback, but students might find
them a little tough.
Perhaps try the July book on African history. I taught a course on
Comparative slave systems and I'll try to dig out some old syllabae.