The technologies of food production may have already been employed by some sub-Saharan peoples by the end of the Pleistocene. A. Food production started with the cultivation of root plants and developed to include the cultivation of cereal crops. B. Pastoralists who moved south across the Sahara to find suitable land for cattle grazing may have also cultivated some crops for food. C. In order to avoid human and animal sleeping sickness, which posed a danger to herders and cattle more and more herders took up cultivation. D. By 1500 B c cereal agriculture was widespread throughout the savanna belt south of the Sahara, and shifting agriculture was used effectively and widely by farmers. E. Hunter-gatherer groups in eastern and southern Africa raided their herding neighbors to acquire cattle and other domesticated animals. F. Slash-and-burn agriculture was initially rejected by farmers because it was too labor-intensive, but once the technique was improved, it expanded gradually to eastern and southern Africa.