Final answer:
The availability of fertile river valleys had a major influence on the development and growth of agriculture in Medieval Africa.
Step-by-step explanation:
The availability of fertile river valleys had a major influence on where and how agriculture developed and flourished in Medieval Africa. Well-watered regions, such as the grassy plains of the savannas and the river valleys, provided the necessary conditions for settled human communities to grow and sustain agriculture over long periods of time. River systems, such as the Limpopo River in southern Africa, were especially important in supporting large civilizations and the cultivation of crops.