The Indian Ocean World and the Monsoon

For more than two thousand years the Indian Ocean was one of the busiest zones of exchange on Earth, linking East Africa, Arabia, Persia, India, Southeast Asia and China. Its rhythm came from the monsoon winds, which blow from the southwest in summer and the northeast in winter, allowing sailors to cross and return within a year. Because merchants often waited months for the winds to change, they settled, married locally and built mixed communities in port cities.

On the East African coast this produced Swahili culture, whose Bantu language absorbed many Arabic words and whose towns, such as Kilwa, built stone mosques and traded gold and ivory. Islam spread to Southeast Asia largely through merchants and Sufi teachers rather than conquest. Unlike many land empires, this network was rarely controlled by one power until the Portuguese arrived after 1498, which is why historians describe it as a relatively open, plural world.