According to the transcript, the three things that linked the Swahili city-states together as a common culture were language, trade, and religion.
This Crash Course World History episode explores the history of Africa south of the Sahara desert, focusing on the Mali Empire and its ruler Mansa Musa, and the Swahili civilization of East Africa. The video challenges Eurocentric biases in historical narratives and emphasizes the importance of considering diverse sources, including oral traditions.
The Swahili city-states exported raw materials such as ivory, animal hides, and timber. They also exported gold and slaves, although the latter was not in huge numbers. They imported finished luxury goods like porcelain and books. The presence of books and a sophisticated level of timber trade (moving trees requires significant organization) reveals a high level of sophistication in their trade networks and society. The existence of built-in bookshelves in some houses further supports this conclusion.
The transcript states that the Swahili language originated with Bantu speakers who migrated from West Africa to East Africa. Their migration introduced ironworking and agriculture, leading to the development of the Swahili city-states. While Arab traders later arrived and introduced Islam, the major Swahili cities were founded well before Islam's arrival in the region. Trade had existed since the first century CE, but the civilization's rapid development began in the 8th century with the arrival of Arab traders seeking access to the Indian Ocean trade network.