En Central Africa, in the equatorial region of the highlands, the great primary forest has been gradually cleared by farmers. The kingdoms that have succeeded in imposing themselves over the centuries are based on the possession of cattle.
Climatic conditions have long been an obstacle to the evolution of societies. But the metallurgical techniques, known and used since 2000 BC. in this part of the continent, allowed itinerant farmers to clear clearings in the great primary forest which had until then been inhabited only by groups of hunter-gatherers of which the Pygmies are the descendants.