The Inca Empire was once the largest civilization of the Western Hemisphere; indeed, some historians consider it to be the largest American civilization ever. Yet, major questions about its history and culture persist, in large part because the Inca did not have a written language and much of their history was passed down orally and later recorded by Spanish colonizers, who often lacked a clear understanding or appreciation of Inca culture. Additionally, the Inca lived high in the Andes Mountains, where some areas were largely inaccessible to earlier archaeologists.

Luckily, a relatively new kind of archaeologist—one who works at high altitudes—can tell us more about this dynamic empire. National Geographic Explorer Maria Constanza Ceruti is one of the top experts in this field. An Argentine with Indigenous Andean ancestry, Ceruti is a mountaineer who ascends cliffs in South America, searching for remnants of Inca society. In the late 1990s, she worked with a team that excavated an active volcano in Peru and discovered mummified children, which are some of the best-preserved mummies ever found. The discovery revealed significant new information about Inca culture.

Understanding the significance of mummies in Inca culture requires understanding how the civilization developed, flourished culturally and was attacked and dismantled by Spanish colonizers. The civilization that predated the Inca, the Wari Empire, declined between 1000 C.E. and 1100 C.E., in part because of a major climate disruption. Warming temperatures and severe drought likely ruined crops and resulted in the empire’s fall. Then, in the 1100s, the Inca people began to consolidate into a small but organized community, establishing a capital in Cuzco. According to Inca tradition, Manco Cápac, an Inca leader and founder of the dynasty, led his people to their new home.

The reach of the Inca remained relatively small for several hundred years, until the 14th century when Emperor Mayta Cápac began taking over adjacent lands and expanding Inca territory. Even with this new growth, however, the Inca would not become an empire until the early 15th century, when Viracocha Inca, who had already made a name for himself as a fierce warrior, came to power. Under his rule, the Inca began taking land south of their capital and bringing neighboring peoples under their control.

The Inca sometimes took land by force, but other times they expanded into new areas peacefully, using diplomacy to gain trust. One way the Inca sometimes earned the support of other Indigenous people was by sacrificing llamas and other animals to the local gods of newly acquired lands. Researchers say that animal sacrifice was an important Inca tradition often used to curry favor.

At the same time, the Inca used force to maintain their holdings. They set up military posts to establish a permanent presence in the lands they took over. If they sensed that people were planning to resist, the Inca forced them to relocate. Inca leaders broke up groups bound by ethnicity and culture by moving some of their members to areas that had already assimilated into Inca society. They also moved people who were loyal to the empire to areas that recently came under Inca rule. Similarly, European colonizers sent groups of White Europeans to the Americas and harmed Indigenous people’s ways of life. Both groups forced assimilation and destroyed local culture to break up resistance efforts.

When Viracocha Inca’s reign ended and his son Pachacuti’s reign began, the Inca Empire reached the peak of its range and advancement. In addition to reviving a road system created by the Wari hundreds of years earlier, the Inca also built new highways connecting the northern and southern areas of their empire. The intricate system included suspension bridges made from vines and tunnels carved from rocks throughout the roadway, which was primarily used by the military.

The Inca also furthered developments in agricultural sciences. They created a series of terraces in the mountains that were used as fields, which made it possible to grow a wide variety of crops at a high altitude. They also had complex irrigation systems that fed water to these fields, including one that used canals to conserve and clean water. The Inca became so prolific at agriculture that they needed to create storehouses to hold extra food. They kept track of their yields with quipus, a system of knots tied in multicolored strands that represented information about food, people and more. While the Inca had no written language, some historians think that the Inca used the quipu for words and narratives.

Inca kings built their own royal estates, which were large complexes of buildings with different functions. One of the most famous of these royal estates is Machu Picchu, a palace likely built by Emperor Pachacuti Inca Yupanqui that is now a UNESCO World Heritage site. The many buildings at Machu Picchu include temples, agricultural structures, administrative buildings and residential houses. The site also includes courtyards and grottos that were likely used for ceremonies and community activities.

Inca kings remained important to the Inca people even in death. Like the ancient Egyptians, Inca leaders were mummified to help the body pass into the afterlife. But whereas Egyptian mummies were intended to be permanently entombed, Inca mummies were brought out to connect people to the gods during important festivals. Inca mummies were dressed in fancy clothing and were often given goods and food in return for helping people reach their gods.

In the 1490s, Huayna Capac took control of the Inca Empire. While he was fighting to maintain the borders of the Inca Empire, he contracted a disease that likely came from Spanish colonizers in present-day Ecuador. The disease killed him and left the Inca Empire vulnerable to Spanish conquest. The empire fell to two brothers, Atahualpa and Huascar, each of whom controlled about half of the territory and battled for control of the full empire. Atahualpa won the battle, but his victory was short-lived, as Spanish conquistadors led by Francisco Pizarro took Atahualpa prisoner in a surprise attack, eventually killing him. The Spanish then installed a series of rulers under the control of Spain.

The instability of this period and the diseases brought by Europeans weakened local rulers who might otherwise have been able to unify and resist the colonizing takeover, though it would take until 1572 for Spanish conquistadors to take all of the land once controlled by the Inca. The Inca resisted by continuing the care of mummified kings until 1559, when Spanish leaders took all of the mummies they could find, displaying them for a time for Spanish colonists in Lima, the colonial capital.

National Geographic Explorer Ceruti did not find the mummies of any Inca kings, but the child mummies she did find are important parts of Inca culture and history. Experts believe that these children were likely sacrificed to the gods in special ceremonies on high peaks called capacocha, or sacrificial ritual site. These sites were on mountain peaks so that the Inca could get as close to the deities as possible. Examiners found that the child mummies were well cared for and wore special clothing and metal jewelry. Because of the level of care the children received, archaeologists have theorized that only children in good health were sacrificed, but later excavations found mummies that had signs of illness or disability. The capacocha ritual is a unique part of Inca culture that was not well understood by the European colonizers who wrote about it, but modern understanding has grown thanks to Ceruti’s work. “Fortunately we have mummies that can speak if we can listen to them properly,” Ceruti once said.

In addition to scaling mountains, Ceruti has also risen to the challenges of working in a male-dominated field, where she has faced discrimination and exclusion. She continuously calls out bullying and misogyny in the academic community and works to increase the visibility of women in science, as well as recognition for people who study once-overlooked regions or topics in the Southern Hemisphere. Ceruti contributes to this effort with a body of work that includes 25 books, hundreds of articles and publications, and ongoing public speaking engagements. She says it is in her blood to continue climbing mountains to explore the Andes and make new discoveries. Through her work, Ceruti has helped deepen our understanding of the Inca and preserve knowledge of their culture for future generations.