Check the following thread to start:
I know from the documentary The Ancient Astronomers of Timbuktu that there were original African manuscripts on other subjects besides philosophy, but it's not my specialization so I can't describe in detail...
its unlikely they have been thoroughly studied because there are possibly hundreds of thousands of manuscripts from timbuktu alone and thousands in the cities of jenne, walata, sokoto, zinder, gao, etc that have only recently been digitized
but in case you'd like to read summaries of the major texts, john hunwick compiled several thousand of these in his well researched volumes titled "Arabic literature of Africa"
in this case you'll need to read "Arabic Literature of Africa: The writings of central Sudanic Africa Vol2" and "Arabic Literature of Africa, Volume 4 Writings of Western Sudanic Africa" entire chapters of both are available on free preview using Google books