Law explains the emergence of Lagos as the leading port of the Slave Coast by looking at where two commercial systems met: European shipping on the Atlantic and the canoe traffic moving goods through the coastal lagoons.

Sixteenth-century Europeans used the Lagos channel to reach Ijebu, buying slaves and cloth there, then abandoned the route in the following century. Lagos itself began as a fishing hamlet before Benin garrisoned it around 1600, perhaps to shut Europeans out of Ijebu and keep that trade for itself. Formal subjection to Benin lasted into the nineteenth century, but Benin's weakening during the eighteenth left the town independent in practice.

Law doubts the assumption that the lagoon route running west to Allada and Whydah predates European contact, treating it instead as a product of European interest drifting westward from Benin. Lagos exported slaves and Ijebu cloth from the 1760s; it became a major port only when Dahomey's military pressure pushed shipments eastward.