Complex sentence: Juan Bautista de Pomar (died 1590) was an historian and writer interested in pre-Columbian Aztec matters after Mexico had been conquered by Spain, based on mentions by Torquemada, we can estimated he was born in 1535.
Split into simpler sentences: Juan Bautista de Pomar (died 1590) was an historian and writer interested in pre-Columbian Aztec matters after Mexico had been conquered by Spain. Based on mentions by Torquemada, we can estimate that he was born in 1535.