The beginnings of this other slavery are lost in the mists of time. Native peoples such as the Zapotecs, Mayas and Aztecs took captives to use as sacrificial victims; the Iroquois waged campaigns called “mourning wars” on neighboring groups to avenge and replace their dead; and Indians in the Pacific Northwest included male and female slaves as part of the goods sent by the groom to his bride’s family to finalize marriages among the elite.

Native Americans had enslaved each other for millennia, but with the arrival of Europeans, practices of captivity originally embedded in specific cultural contexts became commodified, expanded in unexpected ways, and came to resemble the kinds of human trafficking that are recognizable to us today.

The earliest European explorers began this process by taking indigenous slaves. Columbus’s very first business venture in the New World consisted of sending four caravels loaded to capacity with 550 Natives back to Europe, to be auctioned off in the markets of the Mediterranean.

Others followed in the Admiral’s lead. The English, French, Dutch and Portuguese all became important participants in the Indian slave trade. Spain, however, by virtue of the large and densely populated colonies it ruled, became the dominant slaving power. Indeed, Spain was to Indian slavery what Portugal and later England were to African slavery.

Ironically, Spain was the first imperial power to formally discuss and recognize the humanity of Indians. In the early 1500s, the Spanish monarchs prohibited Indian slavery except in special cases, and after 1542 they banned the practice altogether.

Unlike African slavery, which remained legal and firmly sustained by racial prejudice and the struggle against Islam, the enslavement of Native Americans was against the law. Yet this categorical prohibition did not stop generations of determined conquistadors and colonists from taking Native slaves on a planetary scale, from the Eastern Seaboard of the United States to the tip of South America, and from the Canary Islands to the Philippines.

The fact that this other slavery had to be carried out clandestinely made it even more insidious. It is a tale of good intentions gone badly astray.