The Khmer Rouge — A Guide to Cambodia's Dark History Sites
From the fall of Phnom Penh to the Killing Fields of Choeung Ek — a guide to Cambodia's genocide history, with visiting logistics and honest context for travelers.
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Tuol Sleng (S-21) is a former high school. You walk through rooms that became interrogation cells. You see the bed frames where people were chained. Then you see the photographs — thousands of photographs, faces of every prisoner who passed through. Adults, teenagers, children. The Khmer Rouge photographed everyone. The photographs are why we know so much. They are also the hardest thing I've ever looked at as a traveler. I think every visitor to Cambodia should go. Understanding what happened here is part of understanding where this country is now.
— Scott
The Genocide That Destroyed a Quarter of a Nation
Between 1975 and 1979, the Khmer Rouge killed an estimated 1.5 to 2 million Cambodians — roughly a quarter of the country's population — through execution, starvation, forced labor, and disease. These are the places where that history is preserved, documented, and witnessed.
The Khmer Rouge Forms in the Jungle
Rural Cambodia
Saloth Sar — who would become known as Pol Pot — returned from studying in Paris with a radical interpretation of Maoism and began organizing a communist insurgency in Cambodia's remote jungles. The movement called itself the Khmer Rouge (Red Khmers). Drawing on rural peasants resentful of the urban elite, they built a secretive organization in the northeastern highlands.
Secret US Bombing Campaign
Rural Cambodia
The Nixon administration secretly authorized massive B-52 bombing of Cambodia to destroy North Vietnamese supply routes (the Ho Chi Minh Trail). Between 1969 and 1973, the US dropped more bombs on Cambodia than were dropped on Japan in all of World War II. The campaign killed tens of thousands of Cambodian civilians and drove hundreds of thousands of desperate, traumatized rural people directly into the arms of the Khmer Rouge.
Year Zero — Cambodia Erased
Across Cambodia
The Khmer Rouge declared Year Zero — the start of a new society, wiping out all history before their revolution. Money was abolished and banks blown up. Schools and universities were closed. Hospitals were emptied. Religion was banned; Buddhist monks were forced to disrobe or were killed. The concept of family was attacked. Children were separated from parents and formed into youth brigades. Cambodia was to be a purely agrarian society.
Forced Labor, Famine, and Internal Purges
Across Cambodia
Under the Khmer Rouge, Cambodia became a vast forced labor camp. City dwellers — "new people" — were worked to death on irrigation projects and rice fields. Rations were deliberately kept near starvation level. Internal paranoia led to waves of purges: the eastern zones were especially targeted, with entire districts massacred as suspected CIA agents. Vietnam launched military incursions in 1977–1978 in response to Khmer Rouge raids across the border.
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Estimates range from 1.5 to 2.2 million people — between 21% and 25% of Cambodia's entire population. Deaths resulted from execution (particularly of educated people, ethnic minorities, and those deemed politically suspect), forced labor, starvation caused by failed agricultural policies, and disease. The eastern zone purges of 1978 were among the most lethal, with entire villages massacred as suspected Vietnamese agents.
S-21 was Security Prison 21, the Khmer Rouge's main interrogation center, located in a former high school in Phnom Penh. At least 18,000 people were imprisoned there between 1975 and 1979. All prisoners were tortured to extract confessions; virtually all were then executed at Choeung Ek. The Khmer Rouge kept meticulous records and photographs of every prisoner — records that are now displayed at the Tuol Sleng Genocide Museum and used as evidence in genocide trials.
The Killing Fields is a term for the hundreds of sites across Cambodia where Khmer Rouge victims were executed and buried in mass graves. The most visited is Choeung Ek, 15km south of Phnom Penh, which served as the main execution site for S-21 prisoners. Victims were killed to save bullets — beaten, throats cut, or thrown into pits. A memorial stupa at Choeung Ek contains 8,000 skulls. Bone fragments still surface after rain.
Yes — and many Cambodians actively encourage visitors to go. These sites exist precisely because Cambodia wants the world to understand what happened. Visiting thoughtfully — reading the context, listening to the audio guide, treating the sites with respect — is an act of witness and solidarity. The museums operate in part to fund ongoing documentation and survivor testimony programs. Photography is permitted but should be done with sensitivity.
The Extraordinary Chambers in the Courts of Cambodia (ECCC) — a hybrid UN/Cambodian tribunal — convicted S-21 commandant Duch in 2010 (life sentence) and senior leaders Nuon Chea and Khieu Samphan in 2014 and 2018 (also life sentences). Pol Pot died in 1998 before he could be tried. Many Cambodians feel the process took too long and that only a fraction of perpetrators were ever held accountable. The ECCC formally concluded operations in 2022.
The effects are profound and ongoing. The Khmer Rouge systematically killed doctors, teachers, engineers, and other educated professionals — a loss of human capital that set Cambodia's development back by decades. An entire generation of institutional knowledge was destroyed. Today, Cambodia is one of Southeast Asia's fastest-growing economies, but poverty remains significant and political freedoms are constrained. Many Cambodians in their 50s and older survived the period and carry direct trauma. Tourism revenue from Angkor Wat and Phnom Penh is a critical economic driver.