Machu Picchu mystery: why the Inca left the mountain city

Machu Picchu is one of the most astonishing places on Earth. This ancient Inca city, hidden in the mountains of Peru, remained forgotten until American explorer Hiram Bingham discovered it in 1911. Since then, archaeologists have examined its walls, terraces, and temples, yet one question lingers: why did people suddenly leave? Where did its residents go?

How the city came to be—and why it was built

Machu Picchu took shape in the 15th century, when the Inca were at the height of their power. It served at once as a ruler’s residence, a sacred site, and, possibly, a refuge from enemies. Centuries on, its stonework still sits as if laid yesterday. The Inca mastered dry-stone construction, and their techniques continue to surprise researchers.

The city rose high in the mountains, nearly 2.5 kilometers above sea level. That elevation made it more secure, yet complicated the delivery of food and water. And still, despite its advantages, people walked away. Why?

Hypothesis 1: a devastating disease

One widely discussed explanation is an epidemic. When the Spanish arrived in South America in the 16th century, they brought illnesses previously unknown here. Smallpox, for instance, killed millions, including the Inca. Although the Spanish never entered Machu Picchu, disease could have spread via traders or travelers.

If contagion did reach the city, residents might have perished or fled to escape it. So far, however, firm proof is lacking.

Hypothesis 2: relocation elsewhere

Another line of thought suggests people left not because of disease but because they were ordered to do so. As the Spanish conquest unfolded, Inca leaders could have decided to move to a more practical location—such as Vilcabamba, the last major Inca city where resistance continued.

If that is the case, Machu Picchu simply lost its importance, and people departed in search of a better life.

Hypothesis 3: shortages and hard times

A further possibility is scarcity. The Spanish disrupted the roads linking Inca cities, which meant supplies became difficult to deliver to Machu Picchu. Without steady provisioning, everyday life there may have become untenable.

What archaeologists say

When researchers examined the site, they found no traces of warfare or mass death. That points to a voluntary departure rather than a sudden catastrophe. Yet not all belongings were taken, a detail that hints at haste.

Will this mystery be solved?

Today, scholars continue to study Machu Picchu with modern tools. Aerial surveys, for example, scan hidden layers beneath the surface to search for new clues. Perhaps one day, evidence will tip the scales toward one of the hypotheses.

For now, Machu Picchu stands not only as an architectural marvel but also as one of history’s most compelling enigmas.