Ethiopia, shortly after defeating Kush, also became Christianized, and survived as a African only Christian island in a Moslem sea.

In fact, Ethiopia has remained an independent, self-governing state until the present, with the brief exception of the Italian occupation between 1936 and 1941.
The development of man and civilization in Africa was not limited merely to the area in the Northeast.

There is much evidence of cultural contact between people in all parts of the continent.

When the Sahara began to dry out about 2000 B.C., the population was pushed out from there in all directions, thereby forcing the spread of both people and cultures.

Even then, the Sahara did not become a block to communication as has been thought.