The first recorded history appears in the chronicles of North African (Berber) traders, who, from early Roman times, conducted a caravan trade across the Sahara in salt, slaves, gold, and other goods. The southern terminals of the trans-Saharan trade routes were located on the edge of the desert, and from there supplemental trade extended as far south as the edge of the rain forest. The most important terminals—Djenné, Gao, and Timbuctu—grew into major commercial centres around which the great Sudanic empires developed.