The volume's introduction surveys five and a half centuries of African history and makes communication its organising problem. Islam crossed the Sahara and ran down the East African coast, but the editor stresses how unlike the two cases were: in West Africa it entered existing societies, while the towns south of the Juba were foreign settlements around which African populations gathered, which is why the faith travelled so little way inland there.

Elsewhere the story is internal and the evidence thin. Radiocarbon dating had only lately become reliable enough for this period, so much depends on the older layers of oral tradition and on the first outside reports.

Two settlement patterns are drawn out. South of Hausaland lay walled towns supporting ironworking, weaving, dyeing and tanning, with cavalry behind their formation and open ground inside the walls for country people. West of the Volta, village kingdoms and the gold and kola trade of Dyula merchants did comparable work without horsemen.