"I saw here cruelty on a scale no living being has ever seen or expects to see... the island of Hispaniola, once densely populated with native peoples, was laid waste. The Indians died in such numbers — from the pestilence and from the unbearable labors imposed upon them — that of the three million souls I saw on Hispaniola, there remained fewer than two hundred."

— Bartolomé de las Casas, A Short Account of the Destruction of the Indies, 1542

Question: The author's argument in this passage is BEST supported by which of the following historical developments?