Final answer:
Cities like Swahili gained significant wealth through trade networks that connected them to various regions, allowing for the exchange of valuable goods and economic growth.
Step-by-step explanation:
Trade was a huge source of wealth for cities like Swahili due to their strategic location and involvement in long-distance commerce. These cities acted as important trading hubs between the African interior and regions such as Arabia, Persia, India, and Southeast Asia. They exchanged a variety of valuable goods, including gold, iron, copper, salt, hardwoods, ivory, and animal hides, among others. In return, they acquired goods from Asia and sold them locally or further traded them overseas. The trade networks and commerce boosted the economy of the Swahili city-states, making them prosperous and influential.