The Bantu Expansion stands for the concurrent dispersal of Bantu languages and Bantu-speaking people from an ancestral homeland situated in the Grassfields region in the borderland between current-day Nigeria and Cameroon. During their initial migration across most of Central, Eastern, and Southern Africa, which took place between approximately 5,000 and 1,500 years ago, Bantu speech communities not only introduced new languages in the areas where they immigrated but also new lifestyles, in which initially technological innovations such as pottery making and the use of large stone tools played an important role as did subsequently also farming and metallurgy. Wherever early Bantu speakers started to develop a sedentary way of life, they left an archaeologically visible culture. Once settled, Bantu-speaking newcomers strongly interacted with autochthonous hunter-gatherers, as is still visible in the gene pool and/or the languages of certain present-day Bantu speech communities. The driving forces behind what is the principal linguistic, cultural, and demographic process in Late Holocene Africa are still a matter of debate, but it is increasingly accepted that the climate-induced destruction of the rainforest in West Central Africa around 2,500 years ago gave a boost to the Bantu Expansion.
The East African coast is an interface between the continental world of Africa and the maritime world of the Indian Ocean, and the monsoons provided a convenient wind system to link them. It was inhabited by a littoral society that was best placed to play a leading role in economic, social, and cultural interaction, including intermarriage, between the two worlds. Its written history goes back at least to the beginning of the Contemporary Era, and it can be termed Swahili from the beginning of the second millennium when this branch of the Bantu languages spread down the coast to give it linguistic unity. Its speakers were organized in towns and villages from southern Somalia to northern Mozambique, which developed into city-states when there were major upturns in international trade and were integrated in the wider Indian Ocean world. The citizens spoke an “elegant” language that was further embellished through its interactions with Arabic and other Indian Ocean languages and literature. Islam spread with that trade, and mosques became a prominent part of the archaeological remains along the Swahili coast. In the process, the Swahili became thoroughly cosmopolitan. Any attempt to disentangle the different strands, “oriental” or “African”—which are two sides of the dense cultural fabric of the littoral people—is bound to be futile. They are two sides of the Swahili coin. This civilization was partially disrupted by the entry of the Portuguese in the 16th century when they tried to divert the spice trade to their channel around the Cape of Good Hope, but it revived during the 18th and 19th centuries.