 It was summoned by Archbishop Toribio de Mogrovejo in 1581, and met from 15 August 1582 to 18 October 1583.The Council dictated many regulations and principles, centered on the evangelization of the aboriginals and their fair treatment "not like slaves but as free men", as well as their education and instruction in European customs.It decreed that the indigenous languages must be used, and forbade the use of Latin and the exclusive use of Spanish.