When Ulla Lohmann first met the Anga tribe in Papua New Guinea in 2003, the tribe's elders told her to leave. To even get there required a full day's drive, followed by a three-hour hike into the highlands on the west side of the island. After Lohmann, a German photographer and environmental scientist, made the trek, she was politely told that she wasn't welcome. The tribe wasn't accustomed to visitors, and they didn't like their culture to be seen by outsiders.

The reason they disliked guests was the same reason that initially attracted Lohmann to visit them: The Anga are known to mummify their dead. In an ancient ceremony, the members have a long history of converting the bodies of deceased relatives into mummified corpses that sit on a rock ledge near their villages. Such a high perch allows the mummies' families to feel as though their elders are watching over them.

Lohmann retreated when she was asked, but not long after, she went back—and continued to return regularly over the course of a decade. Each time she made her case: She simply wanted to learn from the tribe, to see how its members lived and how they dealt with death.

During her first few visits, she was granted incremental access to learn about the tribe's fragile structure. And after several more treks to the highlands, one of the tribe's elders, a man named Gemtasu, confided something to her: When he died, he wanted to be mummified.

The Anga, a tribe of about 45,000 people, have a mummification process far different from the ancient Egyptians, who would dismantle the body from the inside, remove organs, and then wrap the body in a form of cloth. The Anga mummify their dead sitting up and subject them to three months of smoking over a constantly roaring fire (the smoking helps to preserve the corpse in a tropical culture where it would normally decompose quickly).

The mummification method follows a strict structure. The body is suspended over a fire, and as it bloats, it is poked with wooden sticks to drain its fluids, and later, a stick is used to gently widen the anus to allow the organs to fall out. From start to finish, the mummifiers must remain with the body at all times, and no part of the dead—his fluids, his intestines, or even his body—is allowed to touch the ground, a taboo invitation for bad luck.

The most important part is to keep the face intact. In a culture without photography, the only way to preserve the image of the departed is to physically see their immortal faces. "We have pictures, they have mummies," Lohmann says. "The Anga believe that the spirits roam free during the day and return to their mummified bodies at night. Without seeing the face, the spirits cannot find their own body and would wander eternally."

Mummification was once widespread in Papua New Guinea and other South Pacific islands, most prominent in the 19th and early 20th centuries. Finding a way to preserve physical bodies was seen as a way to keep them from being buried underground, where they could be easily forgotten. But the arrival of Christian missionaries and British and Australian government officers in the middle of the 20th century cast stigma on the practice, both for matters of morality and hygiene.

Even so, Gemtasu, not knowing his exact age but feeling toward the end of his life, believed it was important to keep the tradition alive. Enduring as a mummy would allow him to protect his family. So he taught his grown children how to mummify. He demonstrated on a pig with the help of anthropologists Ronald Beckett and Andrew Nelson, who had studied the process. Gemtasu also asked Lohmann to photograph his own mummification and share his story.

His sons, like many younger members of the tribe, at first resisted. The tribe has turned away from mummification, which is time consuming and labor intensive, to say nothing of the pungent smell of slow-smoked human flesh. The tribe has also experienced regular thinning as its younger members tend to be driven toward port cities more touched by globalization. But Gemtasu continued to urge his sons that mummification, at least for him, was important. "He hassled me long enough so I finally could not do anything else except promising him and making his wish come true," says Awateng, one of Gemtasu's son.

And then, in 2015, Gemtasu died.

Gemtasu's body undergoes mummification in the smoking house.

Photograph by Ulla Lohmann

In keeping with his dying wish, Lohmann returned to Papua New Guinea to witness and photograph the mummification. Seven men, including Gemtasu's grandson, began the process with white clay smeared on their faces, a sign of grief. Under the ceremonial rules, they were not permitted to drink any water—only sugar cane juice from bamboo—and could only eat food cooked in the fire that was smoking Gemtasu. When his skin burned, they used sticks to scrape off the top layer.

Gemtasu with photographer Ulla Lohmann

Photograph by Ulla Lohmann

As Lohmann observed over a series of weeks, the body swelled, blackened, and eventually hardened. The seven men performing the ritual smeared Gemtasu's body fluids onto themselves, an act to preserve his spirit. Under the strict rules, the men were not allowed to wash themselves for the entire three months of mummification, nor to leave the location.

The purpose of mummification in cultures that perform it is usually the pursuit of eternal life, or at least of the continued physical presence for those who have died. In the Anga's case, the final stage is to carry the mummified body, strapped to a chair, to a rock cliff overlooking the village, where the newly deceased join a circle of slowly decomposing elders, their skeletons immortal reminders of the people who once lived.