The Inca civilization, like other ancient Andean groups, practiced artificial mummification as a way of honoring their ancestors and preserving the connection between present and past. The most important Inca mummies, including those of their emperors, were treated as still-living beings—draped in fine textiles and jewelry, served food and drink and carefully tended by their living descendants.

The Incas were not the first Andean culture to make mummies. In fact, the Chinchorro, a culture of hunter-gatherers who lived in the northernmost part of what is now Chile starting around 5000 B.C, began practicing artificial mummification some 2,000 years before the ancient Egyptians.

While the bone-dry, mountainous climate near the coast naturally preserved human and other remains, the Chinchorro learned to extend this process by removing the organs, embalming or drying the flesh and reassembling the bodies. They began by mummifying the remains of children who had died young, but over time they mummified adult remains as well, particularly those of older individuals seen as influential in the life of a community. This process of ancestor-making through mummification was common among Andean groups by the 12th century A.D., when the Inca set up their capital at Cuzco, in what is now southern Peru.

“Artificially preserved mummies from the Andes don’t look like mummies from Egypt,” says Christopher Heaney, assistant professor of Latin American history at Pennsylvania State University. Andean mummies were usually arranged in a fetal position and wrapped in layers of leather or cloth to form bundles. For the Inca in particular, Heaney says, that stillness and solidity was believed to “give the mummies their ability to move through time and continue to shape the lives of the living.”

With their imperial expansion in full swing by the mid-15th century, the Inca used mummification and ancestor-making as a common language to aid in their conquest and subjugation of other Andean groups. According to Inca tradition, the Inca emperor was the sun’s direct descendant, making him the ancestor of everyone he claimed as a subject. When the Inca incorporated a group into their empire, they would claim the group’s ancestral mummies, giving them offerings and bringing the most powerful of them to the Incan capital of Cuzco to worship.

“It was a power move, but it was also nuanced, because what they said they were doing is honoring these other groups' dead,” Heaney says. “The Incas were able to expand because they could speak this language of ancestral relationships.”

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As the empire expanded, the role of the most powerful Inca mummies—known as _illapa—_grew beyond simple ancestor worship. When an Inca emperor died, his successor inherited his power, but not his worldly belongings; these were understood to follow the dead emperor into the afterlife. His family members would then tend to his mummified body, ensuring he was kept in luxurious style even in death.

When the illapa were taken out and assembled together, the new Inca emperor would sometimes show his own power by taking his place and sitting stone-like among his dead predecessors. But these powerful Inca mummies weren’t just male, Heaney emphasizes; instead, they were often preserved in male-female pairs. In order to claim power, a would-be emperor had to marry a prominent Inca woman, sometimes even a relative.

“There was a duality in both Inca and Andean understanding of the universe—that it is male and female together, with their respective powers and abilities, that creates the empire,” he says.

When Spanish conquistadors arrived in the 1530s, the Inca Empire stretched from what is now northern Ecuador to central Chile. “The Spanish were fascinated and unsettled by the Inca cult of their ancestors,” Heaney explains. “They realized that these weren’t just embalmed bodies, but for the Inca and their subjects, they were still cosmically powerful and socially alive.”

After looting and otherwise vandalizing some of the mummies’ tombs, the Spaniards ultimately decided to confiscate all Inca mummies in 1559. The most prominent ones were taken to Lima and stored in a Spanish hospital, where they were likely buried. Meanwhile, stories of the Inca mummies began to spread around the world, largely thanks to Garcilaso de la Vega, the son of a Spanish conquistador and an Inca noblewoman, whose writings were widely translated and republished in the 17th century.

While efforts to excavate the imperial mummies have so far been unsuccessful, another group of Inca mummies took center stage in recent decades—those Inca subjects, particularly children, who were ritually killed by the Incas and placed in mountain graves to serve as emissaries between the living world and the apus, or mountain gods.

The most famous of these child sacrifices, or capacocha, include “Juanita,” the naturally mummified body of a young girl discovered on Mount Ampato in the Peruvian Andes in 1995, as well as the bodies of a 13-year-old girl and two younger children found in a shrine near the summit of the Mount Llullaillaco volcano in Argentina in 1999. Dating to the time of the Inca empire, they are among the best-preserved mummies ever found from any time period in the world.

“We can think of their killings as a show of Inca force, but in dying they also became some of the most powerful beings in the empire,” Heaney says of the capacocha. “The irony is that they’re the ones who survived the centuries, not the emperors themselves.”