When Charles succeeded to the throne of Spain, Spain's overseas possessions in the New World were based in the Caribbean and the Spanish Main and consisted of a rapidly decreasing indigenous population, few resources of value to the crown, and a sparse Spanish settler population. The situation changed dramatically with the expedition of Hernán Cortés, who, with alliances with city-states hostile to the Aztecs and thousands of indigenous Mexican warriors, conquered the Aztec Empire in 1521. Following the pattern established in Spain during the Reconquista and in the Caribbean, the first European settlements in the Americas, conquerors divided up the indigenous population in private holdings "encomiendas" and exploited their labor. Central Mexico and later the Inca Empire of Peru gave Spain vast new indigenous populations to convert to Christianity and rule as vassals of the crown. Charles established the Council of the Indies in 1524 to oversee all of Castile's overseas possessions. Charles appointed a viceroy in Mexico in 1535, capping the royal governance of the high court, "Real Audiencia", and treasury officials with the highest royal official. Following the conquest of Peru, in 1542 Charles likewise appointed a viceroy. Both officials were under the jurisdiction of the Council of the Indies. Charles promulgated the New Laws of 1542 to limit the power of the conqueror group to form a hereditary aristocracy that might challenge the power of the crown.