During the 13th century, the southeast Asian city of Angkor—known for its famed Angkor Wat temple—was home to 700,000 to 900,000 people, new research suggests. This figure makes Angkor one of the largest cities to exist prior to the modern period. It’s also on par with the size of many current-day cities: Boston, for instance, had a population of about 693,000 in 2019.
As Sarah Cascone reports for Artnet News, a new paper published in the journal Science Advances combines 30 years of excavation data with LiDAR (light detection and ranging) scans to reach the new estimate. The ruins of the city, located in what’s now northwestern Cambodia, are renowned for their stone temples, buildings and infrastructure. Thanks to the scanning technology, archaeologists were able to see remnants of structures and landscape features outside of Angkor’s “downtown” area, including buildings crafted from wood and less durable materials.
“When you are on the ground in the main parts of the city center it is quite forested,” says co-lead author Alison K. Carter, an archaeologist at the University of Oregon, in a statement. “As you walk around you can tell there is something in the landscape around you, but you cannot see anything clearly. LiDAR gave us a beautiful grid of mounds and depressions, which we think were little ponds.”
Per Gizmodo’s George Dvorsky, the researchers examined the mounds surrounding Angkor Wat, discovering that the city’s inhabitants built one house on each of the enormous earthworks. These homes probably housed an average of five people.
Using information about how much mound space was available in each time period, the team was able to estimate Angkor’s population changes over time. Final population estimates employed radiocarbon dating and historical archives, as well as ethnographic estimates based on the size of small neighborhood temples that probably each served about 500 people.
“I was amazed by the level of chronological and geographic demographic detail we were able to achieve by combining all these different datasets into a cohesive framework,” the paper’s other lead author, Sarah Klassen, an archaeologist at the University of Leiden, tells Gizmodo.
Speaking with the Atlantic’s Analee Newitz, Klassen adds, “Population is one of those fundamental building blocks to understanding an archaeological site. This number changes everything.”
Angkor was established in the ninth century A.D. Different parts of the city grew at different rates. Early in Angkor’s history, its outskirts, where people grew rice and other crops, expanded quickly. Later, a population spike occurred in the civic-ceremonial center.
That downtown center was home to royalty, as well as craftspeople, dancers, priests and teachers who helped keep the temples and government running, write Carter and Klassen for the Conversation. In addition to the city center and the agricultural outskirts, people also lived along the embankments of roads and canals, possibly working in trade and commerce.
Per Encyclopedia Britannica, Angkor served as the capital of the prosperous Khmer Empire between the 9th and 15th centuries. Ruler Suryavarman II built Angkor Wat in the 12th century. It was originally dedicated to the Hindu god Vishnu but became a Buddhist temple by the end of that century.
As Stefan Lovgren wrote for National Geographic in 2017, climate change contributed to Angkor’s decline, with persistent drought followed by flooding wreaking havoc on its infrastructure. The state of Ayutthaya sacked the city in 1431, after which it was mostly—but never completely—abandoned.
Following the 15th century, Theravada Buddhist monks maintained Angkor Wat as a major pilgrimage site. The city is a Unesco World Heritage site measuring about 150 square miles. It is still inhabited, with some of the people who live in its villages tracing their ancestry back to its golden age.
In recent years, LiDAR scans have helped improve researchers’ understanding of people’s lives in premodern cities and settlements. In 2018, the technology contributed to a major breakthrough in the study of the Maya civilization, as Tom Clynes reported for National Geographic at the time. Archaeologists discovered the remains of more than 60,000 Maya structures in the Petén region of what’s now Guatemala. The findings pointed to a Maya population of as many as 15 million people between 250 and 900 A.D.—three times previous estimates.
The new estimate of Angkor’s size show that its population approached the peak size of ancient Rome, which reached almost 1 million by the second century A.D. Comparatively, London only reached a population of about 600,000 in the early 17th century.
“Studying Angkor's population is important for envisioning the future's urbanism with respect to global climate change,” says co-author Miriam T. Stark, director of the Center for Southeast Asian Studies at the University of Hawaii at Manoa, in the statement. “Angkor was a tropical city that persisted through centuries of political and climatic volatility. Tracking its history and tipping point could help urban planners understand some kinds of constraints that face increasing numbers of the world’s cities.”