Ancient African and Asian plant exchanges across the Indian Ocean had the long-term effect of improving subsistence security throughout the Old World tropics. African botanical contributions are a testament to the skills, knowledge systems and accomplishments of the continent's farmers and herders over the millennia before slave traders arrived along Africa's coasts. The accumulated evidence belies long-standing views of a land-mass and people peripheral to one of humanity's chief accomplishments and of little consequence for intercontinental species exchanges. A revised mental cartography of Africa is needed; one that relocates the continent from a position at the margins of the Indian and Atlantic worlds to one at the crossroads of two of the most extensive maritime networks in global history. The arrival of Iberian caravels in the fifteenth century would catapult Africa's peoples and crops into a new world where Old World tropical staples assumed a new purpose.