PROFITS ON THE FRINGES OF THE SAHARA

The first profits accruing to the Portuguese as a result of their African coastal voyaging came from fishing and privateering off Atlantic Morocco and slaving in the Canaries. Later, when Prince Henrique's captains explored beyond Cape Bojador in the mid-1430s, they found significant colonies of seals – the first hint of new economic opportunities ahead. By the start of the 1440s, the prince's men had commenced slaving razias on African soil and were bartering for gold dust, first at the Rio do Ouro on the coast of Western Sahara, then, more significantly, on the island of Arguim off Mauritania. For the Portuguese, slaves and gold had already become, and would long remain, Atlantic Africa's fundamental attraction.

The discovery of Arguim was a significant advance. Although a barren sandy island that itself produced nothing of commercial value, it possessed a safe anchorage, had reliable wells and was relatively easy to defend. Arguim adjoined rich fishing grounds and offered a convenient base for slaving. But more important commercially was its relative proximity to Wadan, a town some 350 kilometres away in the Mauritanian interior. Wadan was a staging-post for desert caravans passing between West Africa and the Maghrib. Arab and Sanhaja merchants brought horses, cloth and a range of other goods south by this route to exchange for African slaves, and for gold dust from sources near the middle and upper reaches of the Volta river in modern Ghana.