M. A. Shaban pages 109-111 Talks about very large numbers coming from Zaghawa, later known as Kanem and Borno, traveling to Egypt (9th century).
It needs to be stressed that these were not solely north to south migrations as most people assume. This contradicts the idea that native Egyptians were driven out of their country and forced to move south
quote: The strength of the connection, in spite of the enormous distance which separates the valley of the Nile from that of the Niger, plainly indicates a direct relation. The current that flowed so persistently and strongly between Egypt and the Sudan up to the sixteenth century represents something more than a merely commercial interest; it reveals the route of an exodus. The influence and commerce of Morocco and Algeria in the Sudan (countries comparatively near) were for a long time overpowered by distant Egypt. We find undeniable proofs of this among the ancient geographers. Ibn Batouta, a Moor, who visited the countries of the Niger in 1352, relates that at Oualata ' the greater part of the inhabitants wore the beautiful costumes of Egypt.' Now Oualata is only two months' journey distant from Morocco, while the valley of the Nile is at a distance of at least eight months. Again, to destroy the powerful and traditional bias of Egypt towards the Niger and establish the preponderance of the northern countries of Africa would require no less than a Moorish occupation in 1592.