Portugal's lasting legacy for Nigeria, in the end, is its initiation of the transatlantic slave trade.

By 1471 Portuguese ships have reconnoitered the West African coast south as far as the Niger Delta, although they do not know that it is the delta, and in 1481 emissaries from the king of Portugal visitthe court of the oba of Benin.

For a time, Portugal and Benin maintain close relations.

Portuguese soldiers aid Benin in its wars; Portuguese even comes to be spoken at the oba's court.

Gwatto, the port of Benin, becomes the depot to handle the peppers, ivory, and increasing numbers of slaves offered by the oba in exchange for coral beads; textile imports from India; European-manufactured articles, including tools and weapons; and manillas (brass and bronze bracelets that are used as currency, also melted down for objets d'art).

Portugal also may be the first European power to import cowrie shells, which are the currency of the far interior.