Excellent post and point. I responded to one of the posters using the Guaramantes as an example of white and black people cohabiting the Sahara region from ancient times.
In addition I believe the Numidians were also black. These may have been the precursors of the Tuaregs although the latter probably absorbed a great deal of Berber blood, not to mention that they adopted the Hamitic language which is Afro-Asiatic, in other words related to the non-black Berber familly. The original language group of the black people of the region would have belonged to the Bantu or perhaps even Sudanic familly.