Ruins of Kilwa Kisiwani, in Tanzania, which was the first Swahili city state. It was occupied from at least the 8th century CE and eventually became one of the most powerful Swahili settlements along the East African coast. Historically, it was the center of the Kilwa Sultanate, a medieval Swahili sultanate whose authority at its height in the 13th-15th centuries stretched the entire length of the Swahili Coast, from Southern Somalia, to Kenya, Tanzania, Northern Mozambique and Comoros

Ruins of Kilwa Kisiwani, in Tanzania, which was the first Swahili city state. It was occupied from at least the 8th century CE and eventually became one of the most powerful Swahili settlements along the East African coast. Historically, it was the center of the Kilwa Sultanate, a medieval Swahili sultanate whose authority at its height in the 13th-15th centuries stretched the entire length of the Swahili Coast, from Southern Somalia, to Kenya, Tanzania, Northern Mozambique and Comoros.

Kilwa Kisiwani minted its own currency in the 11th to 14th centuries. Some of these coins were discovered in as far as Australia, pointing out the extensive trade the city state commanded.

The Swahili city states' prosperity was based on control of Indian Ocean trade with Arabia, India and China, particularly between the 13th and 16th centuries, when gold and ivory from the hinterland was traded for silver, carnelians, perfumes, Persian faience and Chinese porcelain.