Swahili developed as a lingua franca between several Bantu-speaking tribal groups on the east coast of Africa with heavy influence from Arabic. The earliest examples of writing in Swahili are from 1711. In the early 19th century the use of Swahili as a lingua franca moved inland with the Arabic ivory and slave traders. It was eventually adopted by Europeans as well during periods of colonization in the area. German colonizers used it as the language of administration in German East Africa, later becoming Tanganyika, which influenced the choice to use it as a national language in what is now independent Tanzania.