This paper outlines four stages of the Bantu expansion: first, the initial push through the equatorial forest from the northern to the southern woodlands; second, the occupation of the southern woodland belt from coast to coast; third, the colonization of the Tanzania, Kenya and southern Somali coastline and of the northern sector of the lake region; fourth, the colonization south-wards, north-westwards and north-eastwards from this extended nucleus. The evidence for the first stage is largely linguistic and is likely to remain so. The outlines of the fourth stage can be established very largely from traditional evidence. It is for chronological data concerning the second and third stages that we can now turn hopefully to archaeology. In both these stages the Bantu expansion seems to have coincided fairly closely with the spread of the Iron Age; and, if the spread of the Iron Age through the area north of the southern woodlands can now be traced in something like the detail which we already have for Zambia and Rhodesia, the mystery of the Bantu expansion will have been largely unravelled.