Original: This episode in the conquest and colonization of the Americas began in the early 16th century , but was a more difficult and lengthier exercise in subjugation than the equivalent campaigns against the Aztec and Inca Empires .
Simplified: This part of the conquest and colonization of the Americas began in the early 16th century , but it took more time than the similar campaigns against the Aztec and Inca Empires .