Algeria was something of an exception to the general nature of European colonialism before 1880. More traditional patterns obtained in the rest of Africa, where three different interests intersected. The first of these was trading. As the slave trade declined then came to an end, European trading bases began to deal in vegetable oils instead of slaves, processing African-grown groundnuts and palms. But this only created an intensified demand for slaves within Africa itself, so that the slave trade in sub-Saharan Africa continued well into the second half of the nineteenth century.
