The Bantu expansion is a hypothesis about the history of the major series of migrations of the original Proto-Bantu-speaking group, which spread from an original nucleus around Central Africa across much of sub-Saharan Africa. In the process, the Proto-Bantu-speaking settlers displaced or absorbed pre-existing hunter-gatherer and pastoralist groups that they encountered.

The primary evidence for this expansion is linguistic – a great many of the languages which are spoken across sub-Equatorial Africa are remarkably similar to each other, suggesting the common cultural origin of their original speakers. The linguistic core of the Bantu languages, which comprise a branch of the Atlantic-Congo language family, was located in the southern regions of Cameroon. However, attempts to trace the exact route of the expansion, to correlate it with archaeological evidence and genetic evidence, have not been conclusive; thus although the expansion is widely accepted as having taken place, many aspects of it remain in doubt or are highly contested.

The expansion is believed to have taken place in at least two waves, between about 3,000 and 2,000 years ago (approximately 1,000 BC to AD 1). Linguistic analysis suggests that the expansion proceeded in two directions: the first went across or along the Northern border of the Congo forest region (towards East Africa), and the second – and possibly others – went south along the African coast into Republic of the Congo, Gabon, Cameroon, the Democratic Republic of the Congo, and Angola, or inland along the many south-to-north flowing rivers of the Congo River system. The expansion reached South Africa, probably as early as AD 300.