Final answer:
The Bantu migrations occurred over a period of several thousand years, starting between 3000 and 2000 BCE. The migrations were a spontaneous movement, not an invasion, and were driven by factors such as overpopulation, disease, and changes in climate.
Step-by-step explanation:
The Bantu migrations occurred over a period of several thousand years, starting between 3000 and 2000 BCE. It is believed that there were multiple waves of migration, with the earliest phase consisting of an initial eastern stream and a later western stream. The Bantu people gradually and sporadically moved southward and eastward, settling in central and southern Africa. The migrations were a spontaneous movement, not an invasion, and were driven by factors such as overpopulation, disease, and changes in climate.