Swahili coast
Trading along the Swahili coast between the Swahili-Arabs and Interior tribes stimulated the development of the Interior African tribes. Because of the expansion of trade within the African interior, African rulers started developing politically with an aim to expand their kingdoms and territories in order to be able to have control of the trade routes and mineral sources within their territories. Due to the interaction between the Swahili-Arab traders and interior African tribes, Islam also spread as a religious language. The reign of the Sultans of Zanzibar between 1804 - 1888 and their dominion of the East African Coast from Somalia to Mozambique greatly influenced trade along the Swahili Coast.