The document discusses the history of the slave trade between Europe and Africa from the 15th to 18th centuries. It notes that the slave trade began with the Portuguese joining an existing trade in central and west Africa, supplying slaves as punishment for crimes or prisoners of war. The growth of the sugar industry in the Americas transformed and greatly increased the African slave trade, with African kings fighting wars to supply slaves, known as "Black gold", to meet European demand. Over four centuries it is estimated that around 12 million slaves were taken from Africa to the colonies.