In the 16th century, Portuguese explorers were the first Europeans to begin significant, direct trade with peoples of southern Nigeria, at the port they named Lagos (formerly Eko) and in Calabar along the region Slave Coast. Europeans traded goods with peoples at the coast; coastal trade with Europeans also marked the beginnings of the Atlantic slave trade. The port of Calabar on the historical Bight of Biafra (now commonly referred to as the Bight of Bonny) became one of the largest slave-trading posts in West Africa in the era of the transatlantic slave trade. Other major slaving ports in Nigeria were located in Badagry, Lagos on the Bight of Benin and Bonny Island on the Bight of Biafra. The majority of those enslaved and taken to these ports were captured in raids and wars. Usually, the captives were taken back to the conquerors' territory as forced labour; after time, they were sometimes acculturated and absorbed into the conquerors' society. Slave routes were established throughout Nigeria linking the hinterland areas with the major coastal ports. Some of the more prolific slave-trading kingdoms who participated in the transatlantic slave trade were linked with the Edo's Benin Empire in the south, Oyo Empire in the southwest, and the Aro Confederacy in the southeast. Benin's power lasted between the 15th and 19th centuries. Oyo, at its territorial zenith in the late 17th to early 18th centuries, extended its influence from western Nigeria to modern-day Togo.