mercantilism African slaves Caribbean sugar plantations Middle Passage multiracial society Latin America Sir Robert Clive India circumnavigation Ferdinand Magellan inflation standard of living encomienda potatoes population Treaty of Tordesillas West Indies conquistador Francisco Pizarro Incas smallpox Prince Henry the Navigator joint stock company local, regional, and intra-European trade international trade Ptolemy Marco Polo tariffs Mayan civilization "God, glory, and gold." triangular trade Qing dynasty