A

The Swahili city-states managed to develop mainly due to the boost in trade along the Indian Ocean Basin. Each of the Swahili city-states was an important trading center, including an extensive trading network.

Explanation:

The Swahili city-states on the map are located along the east coast of Africa from modern-day Somalia to Mozambique. Swahili includes eight city-states of Mogadishu, Lamu, Malindi, Mombasa, Zanzibar, Kilwa, Mozambique, and Sofala. Altogether, these were the significant seaports that were used for trade from 500-1500 AD. The Swahili population invaded a narrow strip of coastal land extending from the north coast of Kenya to Dar es Salaam. The city-states substantially prospered from profits because of the trade both inside and outside of ports. There are several factors that led the Swahili city-states to rise, including the extent of the empire’s reach, cultural developments, religious developments, governing structure, as well as the significance of trade.

The growth of the Swahili city-states was primarily caused by the expansion of trade along the Indian Ocean Basin. The gold, ivory, as well as slaves, were traded for the pottery, glassware, and textiles from Persia, India, and China. The kings, who administered the city-states, were dealing with the trade and taxes. With that said, the trade was a focal point for Swahili, as the merchants were the elite members of society, they were rich and wore expensive clothes. Despite the established currency of international trade, the Fatimid dinar, the Swahili produced their own coinage system in silver and copper. The people of the Swahili city-states created a wide-ranging trade network, including the Red Sea, Oman, Shiraz, Goa, Cambay, and China. Such a trade structure enabled increased income that promoted the rise of the city-states.