Present data indicate that the domestication of wild cattle indigenous to the northern Sahara took place approximately eight to nine thousand years ago. This was followed around seven thousand years ago by the domestication of sorghum and millet in the Sahel and Nile regions of the southern Sahara. Other processes of domestication took place on the margins of the tropical forest in central Africa and in the highlands of Ethiopia. As these new technologies expanded southward, there was a moving frontier of interaction between food producers and autochthonous foragers. In some instances these new technologies may have diffused through preexisting networks that linked indigenous foragers. But in most cases it occurred through migration, as populations expanded to exploit the new technological, ecological, and economic advantages these new adaptations allowed. This did not take place in an empty land, however, and in each case complex interactions and negotiations between incoming farmers and indigenous foragers took place for access to resources and rights to settlement. While the details of this interaction varied along with differences in cultural and geographic context, it transformed the linguistic, genetic, and cultural makeup of sub-Saharan Africa after 5000 bce. In some cases, indigenous foragers and their languages disappeared entirely through assimilation or conflict. In others, a longer-lasting frontier was established through which foragers and farmers continued to interact into historic times. Their cultures, languages, beliefs, and worldviews did not remain static and unchanging, however, but were also transformed as new—often hybrid—societies were born. The history and nature of contact varied widely from place to place. In the northern and eastern Kalahari Desert of southern Africa, the data, as presently discerend through archaeological, linguistic, and genetic lenses, support a model of widespread genetic admixture, with flexible associations between culture, subsistence, and language over time.
Drainage development, neotectonics and base-level change in the Kalahari Desert, southern Africa