The Swahili are a coastal East African people whose culture and language emerged from centuries of trade and intermarriage between Bantu-speaking Africans and Arab and Persian merchants across the Indian Ocean. From roughly the 9th to the 16th centuries, independent Swahili city-states (Kilwa, Mombasa, Zanzibar, and others) prospered along the coast, sharing a common language and Islamic faith without ever forming a single kingdom.
The word 'Swahili' comes from the Arabic for 'people of the coast': the language itself is structurally Bantu, but centuries of Indian Ocean trade with Arab and Persian merchants left it with heavy borrowing, especially in vocabulary for religion, law, and trade.