Final answer:
In the 16th century, the Spanish mistreated and abused Native Americans in the Americas. Bartolomé de Las Casas advocated for the fair treatment of native peoples and played a role in ending the encomienda system.
Step-by-step explanation:
In the 16th century, the Spanish, instructed by the King of Spain, mistreated and abused Native Americans in the Americas. They implemented the encomienda system, which allowed Spanish settlers to exploit and control the Native Americans' labor. Bartolomé de Las Casas, a Dominican friar, was one of the system's critics and advocated for the fair treatment of native peoples. His efforts eventually led to the implementation of the New Laws of 1542, which aimed to end the encomienda system and protect the rights of Native Americans.