Guns, Germs and Steel
The rest of Africa: The Sahara Desert was one of several things that made it hard for farming to spread from North Africa to the other parts of Africa. Some farming did spread through Africa, such as cows. Africans also domesticate some crops, such as yams in West Africa and coffee beans in Ethiopia, but their crops were not as good as Eurasia. Most African societies also caught Eurasian diseases like smallpox, although the Khoisan in South Africa did not.