what is the lingua franca of much of eastern africa
Swahili, known as Kiswahili to its speakers, is used throughout large parts of East Africa and the eastern Democratic Republic of the Congo as a lingua franca, despite being the mother tongue of a relatively small ethnic group on the East African coast and nearby islands in the Indian Ocean. At least as early as the late 18th century, Swahili was used along trading and slave routes that extended west across Lake Tanganyika and into the present-day Democratic Republic of Congo. Swahili rose in prominence throughout the colonial era, and has become the predominant African language of Tanzania and Kenya. Some ethnic groups now speak Swahili more often than their mother tongues, and many, especially in urban areas, choose to raise their children with Swahili as their first language, leading to the possibility that several smaller East African languages will fade away as Swahili transitions from being a regional lingua franca to a regional first language.