Colonial administration was exercised through government entities in both Spain and America. In Spain, institutions like the Seville Contracting House and the Council of the Indies oversaw colonial affairs. In America, the Royal Audiences, Presidencies, Viceroyalties, and Cabildos administered the colonies. To exploit resources and control relations between Spaniards, indigenous peoples, and blacks, systems of exploitation like slavery, encomienda, resguardo, and mita were established. Due to mistreatment and overwork, many indigenous peoples died, so Spaniards began importing black slaves from Africa in the late 16th century.