Great Zimbabwe
A Shona kingdom of southern Africa built a great stone-walled city, prospering by selling gold and ivory into the Indian Ocean trade.

Todinirunganga · CC BY-SA 4.0 · Source
Great Zimbabwe was the centre of a Shona kingdom that flourished on the Zimbabwe plateau in the 13th–15th centuries. High walls and a conical tower of granite laid without mortar still stand. Gold and ivory from the plateau went to Sofala and Kilwa on the East African coast and into the Indian Ocean trade, and Chinese porcelain and Persian pottery have been found at the site. It declined in the mid-15th century and was succeeded by the Mutapa kingdom. Colonial-era claims that Africans could not have built it were refuted by archaeology, and the modern country of Zimbabwe takes its name from it.