Although Spain got off to a slow start, with only trinkets plundered from savages on Caribbean islands to show for their efforts, they quickly switched to pursuit of precious metals. Continued efforts for the westward passage to India revealed wealthy civilizations on the Mexico mainland and northern South America.
Spanish conquistador Hernán Cortés conquered the Aztec Empire 1519–1521. Following in the moral tradition of the Inquisition, as a demonstration designed to invoke fear, Cortés massacred thousands of unarmed nobility on his way to Tenochtitlan, the capitol city, for a meeting with Moctezuma II, the Aztec ruler.
Though death tolls and situations varied, such atrocities would become commonplace by conquerors, and carried on in wars throughout the world to the present day. Metals may be precious but human life is always cheap.
Spanish conquistador Francisco Pizarro, on his 3rd attempt, conquered the Peruvian Inca Empire in the 1533. In 1532, Pizarro invited Atahualpa, the Incan emperor, to parley. Instead of diplomacy, Atahualpa received an ambush. Pizarro slaughtered Atahualpa’s entire retinue. Pizarro held the emperor for ransom, which was paid.
Pizarro then decided to kill Atahualpa. Atahualpa was to be burned alive, but was told that if he converted to Catholicism, he would be spared. As the Incas believed that a soul could not go to the afterlife if its body was burned, Atahualpa agreed; whereupon Atahualpa was garroted instead.
By the end of the 16th century, Spain wielded effective power over much of the hemisphere from Florida and Southern California down through South America, Brazil excepted.
The Spaniards at first merely plundered the natives of all their portable wealth. After quickly exhausting that, they introduced European mining methods to gouge silver out of the ground in Mexico and the Andes.
Unlike the Portuguese, who lacked population to spare, the Spanish colonized the areas they conquered. That meant forcibly importing their civilization: people, equipment, firearms, institutions, religion, crops, livestock, and disease.
Before the Spanish arrived, the native population numbered well over 25 million. By the end of the 16th century only a few million indigenes remained.
Beginning in 1501, African slaves were shipped over to address the labor shortage. By 1600, the majority of people in the West Indies were Africans and those of mixed races.