There was a very small market for African slaves as domestic workers in Europe, and as workers on the sugar plantations of the Mediterranean. However, the Portuguese found they could make considerable amounts of gold transporting slaves from one trading post to another, along the Atlantic coast of Africa. Muslim merchants had a high demand for slaves, which were used as porters on the trans-Saharan routes, and for sale in the Islamic Empire. The Portuguese found Muslim merchants entrenched along the African coast as far as the Bight of Benin.