Step-by-step explanation:
The expansion is believed to have taken place in at least two waves. between about 3,000 and 2,000 yrs ago. Linguistic analysis duggest that the expansion proceeded in two directions the first went across the Congo forest region (towards East Africa) and the second and possibly others went South along the African coast into Gabon, 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.