The Kingdom of Kongo was divided into six provinces and included some dependent kingdoms, such as Ndongo to the south. Trade was the main activity, based on highly productive agriculture and increasing exploitation of mineral wealth. In 1482, Portuguese caravels commanded by Diogo Cão arrived in the Congo[1] and he explored the extreme north-western coast of what today is Angola in 1484.[2] Other expeditions followed, and close relations were soon established between the two states. The Portuguese brought firearms and many other technological advances, as well as a new religion (Christianity); in return, the King of the Congo offered plenty of slaves, ivory, and minerals.