Why did most of Africa remain unbroken?

The most developed was the north of Africa, which has long been involved in the cultural exchange of the countries of the Mediterranean basin. Similarities of states more often arose on the ocean coasts. However, most of Africa had a different world – the world of “black” equatorial Africa. Severe climate, many dangerous diseases, tropical forests and sparse soils did not allow local tribes to reach a high stage of development. Some of them led the lives of people of the Stone Age.