Pastoralism arose in africa during the classical era primarily in response to:

Pastoralism arose in Africa as a response to climate and as a successful strategy to support population on the less productive land and to help it adapt on the environment. Pastoralism is the branch of agriculture concerned with the rising of livestock: the care and use of cattle, camels, yaks, sheep and llamas. It also has to do with moving the herds in search for fresh food and water, in contrast to pastoral farming, settled in one place (farm). Patoralists and their animals, for example, gather in savannas when there is abundance of rain, and in the dry season, everyone goes their way.

Idon’t know this answer but you can ask google i bet the answer is on there