sentences:  Although gold was the primary and abiding merchandise sought by the Portuguese, by the early 16th century they were participating in the slave trade for bearers to carry manillas to Africa's interior, and gradually manillas became the principal money of this trade.The Portuguese were soon shouldered aside by the British, French, and Dutch, all of whom had labor-intensive plantations in the West Indies, and later by the Americans whose southern states were tied to a cotton economy.A typical voyage took manillas and utilitarian brass objects such as pans and basins to West Africa, then slaves to America, and cotton back to the mills of Europe.