Like Da Gama, on his second voyage Columbus introduced shocking practices, including cutting off Natives’ hands if they did not pay his quarterly gold tax. He started the trans-Atlantic slave trade — of Native people, from west to east — by sending 5,000 Arawaks in chains to Spain and Majorca. A particularly repellent aspect of the trade was sexual: as Columbus noted, “girls from nine to ten are now in demand.” Partly as a result, the Native population of Haiti fell from perhaps 3,000,000 in 1491 to fewer than 500 by 1535. His son then started the trans-Atlantic slave trade from east to west, in Africans.

All this might prompt students to discover when and why their state adopted Columbus Day. Should it join the movement to change the holiday’s name to honor Native Americans? Educators can help them avoid falling for the excuse that everyone accepted slavery in 1493. The Arawaks didn’t! Neither did, famously, Bartolomé de las Casas, the Spanish priest who said of the slave trade, “The acts we committed in the Indies stand out among the most unpardonable offenses ever committed against God and mankind, and this trade as one of the most unjust, evil, and cruel among them.”

Thinking seriously about Columbus is important, because he introduced four processes that transformed the modern world:

1. the taking of land, wealth, and labor from indigenous peoples an ocean away;
2. the transatlantic slave trade;
3. demeaning on racial lines the people he had subjected, and
4. the “Columbian exchange” — a period of cultural and biological exchanges between the New and Old Worlds. Exchanges of plants, animals, diseases, ideas, and technology transformed European and Native American ways of life. The Columbian Exchange impacted society and culture on both sides of the Atlantic. New crops, changes in warfare, and increased mortality rates are a few examples of the impact of the Columbian Exchange on Europeans, Africans, and Native Americans.

Units on Columbus must emphasize these four crucial points, for they are critical to understanding subsequent American and world history.