Final answer:
In Medieval Africa, trade significantly contributed to the spread of Islam, as it fostered shared customs and language among traders, enhancing cooperation and trust.
Step-by-step explanation:
Trade was an important driving force for the spread of Islam in Medieval Africa. The widespread adoption of Islam facilitated trans-Saharan trade by providing Muslim merchants, traders, and caravanners with a shared set of customs, laws, traditions, and language, which promoted trust and allowed for increased trade among distant peoples. Furthermore, the spread of Islam reached various regions primarily through activities of merchants, traders, scholars, and missionaries, rather than by military conquest.