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A team at Monash University created stunning computer graphics depicting daily life at Angkor Wat in the late 12th century, before the Khmer exodus.

Staggering Statistics Revealed On Angkor Wat and the Khmer Exodus


Angkor Wat was the enormous capital city of the Khmer Empire, located in modern day Cambodia. Now, a new study has attempted to understand the Khmer exodus, whereby the ancient mega-city of almost a million inhabitants was abandoned. Their new data points to the metropolis having been vacated over a long period of time. Our question is, how on Earth have they extracted this information from the iconic crumbling jungle temples we associate with ancient Cambodia

Before it was abandoned in 1431 AD, Angkor Wat is estimated to have been home to a staggering 700,000 to 900,000 inhabitants. The new study was published in the journal Science Advances, and the team of researchers from the University of British Columbia reached their conclusions after creating a “demographic model of the demise of the medieval super-city” in their quest to understand the Khmer exodus.

Image of the Ta Prohm temple, part of the thriving city that was Angkor Wat before the Khmer exodus. (Benot / Adobe Stock)

Mapping the Khmer Exodus

Dr. Sarah Klassen, the lead author of the new paper, said the capital of the Khmer Empire represented “one of the largest pre-modern cities in the world, built up over several centuries of growth at different rates.” The new model revealed that Angkor Wat housed between 700,000 and 900,000 people during its zenith in the 13th century. Delighted with their results, the researcher suggests that her team’s new technique for modeling “urban center growth and decline” may be applied not just to understanding the Khmer exodus, but also to other pre-modern cities across the ancient world.

This new type of data offers insights into the patterns of rise and decline in ancient cities, but in this case, also into the nuances of Khmer social complexity. The study suggests that Angkor, the ancient capital of the Khmer Empire, “suffered a gradual decline” and one of the most interesting aspects of this research is that it illustrates over how long Angkor Wat was abandoned. Archaeologists and historians have long debated whether the collapse of the empire came after the 1431 AD invasion by Thai forces, but the new model reveals “a slow and prolonged exodus of its inhabitants dating back to the start of the 14 th century.”

In order to understand the so-called Khmer exodus, the study assessed the densities of people per hectare in the greater Angkor region over time. (C. Pottier, D. Evans and J-B. Chevance / CC BY-ND)

Looking to the Earth for Answers to Understand the Khmer Exodus

This wasn’t like most archaeological projects, which are usually built upon previous research and papers. Until this study no comprehensive demographic analysis of Angkor had ever been undertaken. One of the main reasons for this is that most of the ancient city’s non-religious architectural structures, that were not built in stone, rotted away over 500 years ago. Thus, the team of archaeologists really did have to chop their way through an unexplored jungle, with no previous path to follow. 

At this stage it seems pertinent to ask how the archaeologists could possibly chart “a slow exodus” from an ancient city if no organic samples are available. Well, although almost all the organic materials have rotten away, the scientists were able to chart the gradual decline in human activity using soil and sediment samples taken across the region. According to Klassen and her team, quoted in The Daily Mail, the available data rendered conventional population size and density estimation models “impossible”.

Reconstruction one a medieval shrine south of Angkor Wat. (Monash University / CC BY-NC-ND)

Reappraising the Shifting Human Tides of Ancient Angkor

My understanding has always been that humans are great at calculating small data sets, but when things get too fast, too far away or too small, our brains become worthless as calculators. How then did the team come to the conclusion that the city had been abandoned slowly, with the aid of nothing more than field solid samples? Of course, the answer is those robots with AI (Artificial Intelligence) brains again.

Machine learning algorithms were programmed and set in motion, tasked with scanning recent LIDAR imagery and data (Laser Imaging, Detection, And Ranging), and the AI created models of the city’s growth and decline over time. The AI was also able to identify three ancient occupation zones with distinctly different growth rates. The first two zones were the outer embankments and metropolitan area, and the inner civic-ceremonial center was where the famous and large stone temples were built for the Khmer ruling dynasty.

In conclusion, the team of researchers suggest that that it may have “taken several centuries for Angkor’s population to reach its peak.” But that’s not all the team learned by using AI technology. Rather than a mass Khmer exodus, provoked by some sudden catastrophic event, their data has shown that the population at Angkor Wat declined slowly before becoming completely abandoned and reclaimed by the jungle after 1431 AD.

Top image: A team at Monash University created stunning computer graphics depicting daily life at Angkor Wat in the late 12th century, before the Khmer exodus. Source: Monash University / CC BY-NC-ND

By Ashley Cowie



Yes, but, AI is simply a computer program which has been written by a modern human being.
This human being sees the world and history through a set paradigm.

We are placing too much emphasis on AI solving many questions of the past.
AI is not as magic as we are being led to believe.

ashley cowie's picture


Ashley is a Scottish historian, author, and documentary filmmaker presenting original perspectives on historical problems in accessible and exciting ways.

He was raised in Wick, a small fishing village in the county of Caithness on the north east coast of... Read More

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