A second cause of weakness in Portuguese Africa was the effects of three centuries of Atlantic slave trade which had roots in the older African slave trade. Once the Atlantic triangular trade got underway, many Portuguese (including many Brazilian traders) in Africa found little incentive to engage in any other kind of profitable economic activity. The economies of Guinea, Angola and Mozambique became almost entirely devoted to the export of slaves to the New World (plus gold and ivory where they were available) while on the islands, slaves were used to grow sugar for export. Colonial authorities did nothing to stop the slave trade, which had sympathisers even among the several native African tribes, and many became wealthy by supporting it, while the traders themselves generated huge profits with which they secured allies in Africa and Portugal.