Final answer:
Trade, including the slave trade, brought wealth to African coastal empires through the acquisition of valuable resources and human labor. This trade also led to the emergence of powerful chieftains and merchants who profited from the trade of enslaved people.
Step-by-step explanation:
Trade, including the slave trade, contributed to African coastal empires gaining wealth and power by bringing valuable resources and human labor to these empires. Many kingdoms on the African coast engaged in the slave trade and expanded their trading activities to capture and sell enslaved individuals to European slave traders. The demand for enslaved people also led to the emergence of powerful African chieftains and merchants who profited from trading enslaved people for European goods. Additionally, the slave trade brought European firearms and manufactured goods to Africa, which militarized states and transformed African society.