Complex sentence: The Indians of the Americas were still heavily exploited, with significant population declines, which arose the conscience of Bartolomé de Las Casas, a former Encomendero who regretted his ways and spent the rest of his life working to bring freedom back to the Indians.
Split into simpler sentences: The Indians of the Americas were still heavily exploited, with significant population declines. This arose the conscience of Bartolomé de Las Casas, a former Encomendero who regretted his ways and spent the rest of his life working to bring freedom back to the Indians.