Benguela, a Portuguese fort from 1587 which became a town in 1617, was another important early settlement they founded and ruled. The Portuguese would establish several settlements, forts and trading posts along the coastal strip of current-day Angola, which relied on slave trade, commerce in raw materials, and exchange of goods for survival. The African slave trade provided a large number of black slaves to Europeans and their African agents. For example, in what is now Angola, the Imbangala economy was heavily focused on the slave trade.
European traders would export manufactured goods to the coast of Africa where they would be exchanged for slaves. Within the Portuguese Empire, most black African slaves were traded to Portuguese merchants who bought them to sell as cheap labour for use on Brazilian agricultural plantations. This trade would last until the first half of the 19th century. According to John Iliffe, "Portuguese records of Angola from the 16th century show that a great famine occurred on average every seventy years; accompanied by epidemic disease, it might kill one-third or one-half of the population, destroying the demographic growth of a generation and forcing colonists back into the river valleys".
The Portuguese gradually took control of the coastal strip during the 16th century by a series of treaties and wars, forming the Portuguese colony of Angola. Taking advantage of the Portuguese Restoration War, the Dutch occupied Luanda from 1641 to 1648, where they allied with local peoples, consolidating their colonial rule against the remaining Portuguese resistance. In 1648, a fleet under the command of Salvador de Sá retook Luanda for Portugal and initiated a conquest of the lost territories, which restored Portugal to its former possessions by 1650. Treaties regulated relations with Kongo in 1649 and Njinga's Kingdom of Matamba and Ndongo in 1656. The conquest of Pungo Andongo in 1671 was the last major Portuguese expansion
