By 1471 Portuguese ships had reconnoitered the West African coast south as far as the Niger Delta, although they did not know that it was the delta, and in 1481 emissaries from the king of Portugal visited the court of the oba of Benin. For a time, Portugal and Benin maintained close relations. Portuguese soldiers aided Benin in its wars; Portuguese even came to be spoken at the oba's court. Gwatto, the port of Benin, became 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 were used as currency and also were melted down for objets d’art). Portugal also may have been the first European power to import cowrie shells, which were the currency of the far interior.
Benin profited from its close ties with the Portuguese and exploited the firearms bought from them to tighten its hold on the lower Niger area. Two factors checked the spread of Portuguese influence and the continued expansion of Benin, however. First, Portugal stopped buying pepper because of the availability of other spices in the Indian Ocean region. Second, Benin placed an embargo on the export of slaves, thereby isolating itself from the growth of what was to become the major export from the Nigerian coast for 300 years. Benin continued to capture slaves and to employ them in its domestic economy, but the Edo state remained unique among Nigerian polities in refusing to participate in the transatlantic trade. In the long run, Benin remained relatively isolated from the major changes along the Nigerian coast.