The Khmer Rouge and Pol Pot: What Happened in Cambodia from 1975 to 1979?

Prepared by the NovAsia Editorial Team

On 17 April 1975, armed Khmer Rouge forces entered Phnom Penh. To a city exhausted by civil war, their arrival could initially look like the end of the fighting. Within hours, it became clear that this was not a peaceful transfer of power. Hospitals, homes and streets were emptied. Residents of the capital, including patients, older people and children, were forced to leave on foot for the countryside.

Over the next three years, eight months and twenty days, the leadership of Democratic Kampuchea attempted to create a radical agrarian state without ordinary cities, markets, money, private property or independent civic life. People were divided into categories, families were separated and labour was organised through collectives under conditions of chronic food shortages and inadequate medical care. Hundreds of thousands were executed as real or imagined enemies. Many more died from starvation, illness and exhaustion.

The exact death toll cannot be established with certainty. Research and memorial organisations commonly estimate that approximately 1.5 to 2 million people died, representing a substantial share of Cambodia's population at the time. The catastrophe is inseparable from the name Pol Pot, but it was not the work of one individual. It involved the party leadership, security apparatus, regional administrations, prisons, labour sites and a system of command that turned suspicion and violence into routine instruments of government.

How the Khmer Rouge came to power

The Khmer Rouge did not suddenly appear in April 1975. Their rise grew out of decades of political struggle, decolonisation, the Cold War and conflict across Indochina. A Cambodian communist underground existed before the movement acquired the name by which it is now known. In 1960, a group including Saloth Sar, the future Pol Pot, and Nuon Chea formed the core of what became the Communist Party of Kampuchea.

The political situation changed dramatically after the coup of 1970. While Prince Norodom Sihanouk was abroad, General Lon Nol took power and Cambodia became the Khmer Republic. Sihanouk, still regarded by many rural Cambodians as the legitimate national leader, allied himself with his former communist opponents. His calls to support the resistance helped the Khmer Rouge broaden their social base, although effective control within the movement remained with the party leadership.

Cambodia's civil war unfolded alongside the war in Vietnam. North Vietnamese and Viet Cong forces operated on Cambodian territory, the United States carried out extensive bombing, and state institutions weakened. Rural communities faced destruction, displacement and increasing distrust of Lon Nol's government. The Khmer Rouge used this crisis to recruit fighters and promised independence, order and social justice.

By early 1975, Phnom Penh was crowded with refugees and largely encircled. Once the capital fell, the Khmer Rouge leadership could extend policies already tested in areas under its control. Victory did not lead to reconstruction of the existing state. The new authorities instead set out to dismantle the society they had inherited.

Pol Pot and the project of Democratic Kampuchea

Saloth Sar was born in 1925. He was educated in Cambodia and later studied in France, where he became involved with communist circles. After returning home, he worked as a teacher and participated in underground politics. He became party secretary in 1963, later adopted the revolutionary name Pol Pot and emerged as the regime's central political figure.

After the Khmer Rouge victory, the country was renamed Democratic Kampuchea. Yet most citizens initially did not know who governed them. Authority spoke in the name of *Angkar*, meaning “the Organisation”. The party structure was secret, and orders were presented as the will of an impersonal, almost all-knowing body. This secrecy intensified fear. People often did not know who had accused them, where they were being sent or whether any decision could be challenged.

The leadership aimed to transform Cambodia rapidly into a self-sufficient agricultural society. It rejected gradual reform. Money and independent trade were abolished, banks closed and private property confiscated. Religious institutions, schools, cultural organisations and professional networks lost their autonomy.

The expression “Year Zero” is often used to describe this rupture, although it is better understood as a shorthand for the regime's attempt to erase the old order than as the complete official title of a single policy. Previous knowledge and social experience became suspect. An educated person, city resident, civil servant, monk or specialist could be treated not as someone needed to rebuild the country, but as a carrier of dangerous habits and loyalties.

Pol Pot served as prime minister of Democratic Kampuchea from 1976 and played a central role in setting policy. He worked alongside Nuon Chea, Ieng Sary, Khieu Samphan, Son Sen and other senior figures. Their responsibilities differed, but the catastrophe cannot be explained by Pol Pot's personality alone. The system functioned through ideology, party discipline, secret policing, regional administration and a constant search for internal enemies.

The day Cambodia's cities were emptied

The evacuation of Phnom Penh was the regime's first and most visible nationwide act. Soldiers told residents that they would leave only briefly because of a possible American bombing campaign or a food shortage. In reality, the transfer formed part of a much broader policy. Cities were regarded as centres of inequality, commerce, foreign influence and political unreliability.

People were often given little time to collect belongings. Patients were forced from hospitals, families lost one another in the crowds and long columns moved through the heat with inadequate food and water. Many did not know their destination. Some were directed towards their home provinces; others were assigned to areas where labour was required. Forced evacuations took place not only in Phnom Penh but in other towns during 1975.

Displaced urban residents were often called “new people” or “17 April people”. They were contrasted with “base people”, meaning rural residents of areas previously controlled by the Khmer Rouge. The distinction was applied differently from place to place and changed over time, but “new people” generally had fewer rights, received poorer rations and faced tighter supervision. Social origin became an administrative label that could determine work conditions and chances of survival.

The emptying of cities was not merely symbolic. It stripped people of property, occupation, familiar surroundings and social networks. A person placed in an unfamiliar cooperative became dependent on food distribution, permissions and local cadres. Forced transfer was therefore both an economic policy and a method of control.

Life in cooperatives and labour sites

Rural Cambodia was reorganised into cooperatives, mobile work brigades and major construction zones. People grew rice, dug canals, built dams and cleared new fields. The leadership demanded dramatic increases in agricultural production and sought to export part of the crop. These targets frequently ignored soil conditions, seasonal realities, available tools and the experience of the workers.

The working day could begin before sunrise and continue into the night. Many former city residents had no experience of heavy agricultural labour. Food rations depended on local officials and production targets. Even where rice was harvested, workers did not control it. Malnutrition weakened the population, increased vulnerability to disease and made ordinary injuries potentially fatal.

The medical system had been destroyed along with other professional institutions. Doctors and pharmacists were killed, forced to conceal their education or assigned to unrelated work. Treatment was often provided by untrained personnel, and medicines were scarce. Malaria, intestinal disease, oedema, severe malnutrition and complications from forced labour killed vast numbers of people without a specific execution order.

The regime also tried to weaken the family as an independent social unit. Children were placed in separate work groups and taught loyalty to Angkar. Spouses could be assigned to different brigades, communal dining replaced family meals and private conversation attracted suspicion. The tribunal later found evidence of a nationwide policy regulating marriage. Couples were matched administratively, ceremonies were conducted collectively and refusal could lead to punishment. Sexual violence occurred within these forced marriages.

Religious life was suppressed. Buddhist monasteries were closed or repurposed, monks were forced to disrobe, Cham Muslim practices were prohibited and Christian communities were also persecuted. In a society where pagodas, ancestral observance and religious festivals structured community life, this represented not only a ban on worship but the destruction of a familiar moral and social order.

The security system and S-21

The Khmer Rouge regime did more than exploit labour. It created a nationwide network of security centres, prisons and execution sites. People were accused of links to the previous government, foreign intelligence services, Vietnam or internal opposition. Evidence was often unnecessary. Suspicion, denunciation, family connection or a name extracted from another prisoner could be enough for arrest.

The best-known prison was S-21 in Phnom Penh, established in a former school complex. The site is now the Tuol Sleng Genocide Museum. Museum records indicate that roughly 15,000 to 20,000 prisoners passed through the centre. They were detained, interrogated and tortured as alleged political enemies, including senior cadres of the regime itself. Collective punishment led to the arrest of spouses and children. When the prison was discovered in January 1979, only a small number of survivors were found.

S-21 is notable not only for its violence but for its bureaucracy. Prisoners were photographed, registered and forced to produce confessions. Interrogators demanded confirmation of predetermined stories about espionage and conspiracy. Under torture, prisoners named other people, expanding the cycle of arrests. Documents left behind during the Khmer Rouge withdrawal later became crucial evidence of how the security system operated.

Internal purges intensified in 1977 and 1978. Economic failures were explained not as policy mistakes but as sabotage. Party officials, soldiers and regional cadres were themselves recast as enemies. The Eastern Zone was subjected to particularly severe repression because residents and officials were suspected of sympathy with Vietnam. A revolution that claimed to create unity increasingly governed through the idea of hidden betrayal.

The phrase “killing fields” is commonly associated with places of mass execution and burial. Choeung Ek, outside Phnom Penh, is one of the best known and received prisoners from S-21. But the violence was not confined to a few memorial sites. Researchers have documented hundreds of detention centres and thousands of mass graves across Cambodia. The intensity and local practices differed, yet the system was national in reach.

Who was targeted?

Repression affected almost every part of Cambodian society. In the first months, officials and soldiers of the Khmer Republic and their families were at particular risk. Teachers, doctors, engineers, foreign-language speakers and urban residents could all be treated as suspect. The familiar claim that people were killed simply for wearing glasses is an oversimplification, but it reflects the broader fear attached to signs of education and former status.

Most victims were ethnic Khmer. They died through execution, starvation, overwork, disease, forced transfer and imprisonment. At the same time, particular national and religious groups faced targeted persecution. Ethnic Vietnamese communities were expelled and killed. Cham Muslim communities were dispersed, their religious practices prohibited and many of their members massacred. Buddhist monks and other religious groups were persecuted as well.

This is where the term *genocide* requires care. In ordinary language, “the Cambodian genocide” often refers to the entire mass catastrophe of 1975–1979. Under international law, genocide requires proof of an intention to destroy, in whole or in part, a national, ethnic, racial or religious group. Political and social categories are not included in the same way.

The Extraordinary Chambers in the Courts of Cambodia found genocide against the Vietnamese and, in its findings concerning particular defendants and events, against the Cham. It also found a broad range of crimes against humanity, including murder, extermination, enslavement, deportation, unlawful imprisonment, torture, persecution, forced transfer, enforced disappearance, forced marriage and other inhumane acts.

Legal precision does not reduce the suffering of the Khmer majority. It distinguishes categories of crime and the evidence required to establish them. Deaths from hunger and disease should not be treated as a natural disaster. Food deprivation was connected to forced collectivisation, unrealistic production plans, seizure of crops, destruction of markets, population transfers and restrictions on independent survival. Not every victim was executed, but state policy created the conditions for mass death.

Why the regime collapsed

Relations between Democratic Kampuchea and Vietnam moved rapidly from revolutionary alliance to open conflict. The two countries had border disputes, historical mistrust and competing regional ambitions. Pol Pot's leadership regarded Vietnam as the principal external enemy and blamed internal conspiracies on Vietnamese influence. Cambodian forces attacked Vietnamese border communities and killed civilians.

In late December 1978, Vietnam launched a major invasion with support from Cambodian opponents of Pol Pot. Democratic Kampuchea's army retreated quickly. On 7 January 1979, Vietnamese forces and their Cambodian allies entered an almost deserted Phnom Penh. Khmer Rouge rule in the capital ended.

The fall of the regime did not bring immediate peace. Khmer Rouge forces withdrew towards the Thai border and continued armed resistance. Cold War politics complicated the international response. Vietnam's presence was opposed by many states, China supported Vietnam's adversaries and a coalition that included the Khmer Rouge retained Cambodia's international representation for a time. For survivors, this meant that the movement responsible for the catastrophe did not simply disappear from politics in 1979.

Civil war and the movement's fragmentation continued for years. The Paris Peace Agreements were signed in 1991, but the last Khmer Rouge structures did not collapse until the late 1990s. Pol Pot died in 1998 in an area controlled by the movement, never having faced the later internationally supported tribunal.

Justice, memory and long-term consequences

In 1979, a revolutionary tribunal in Phnom Penh convicted Pol Pot and Ieng Sary in absentia. The proceedings took place soon after the invasion, without the accused present, and did not gain broad international recognition. Establishing a later court required years of negotiation between the Cambodian government and the United Nations.

The Extraordinary Chambers in the Courts of Cambodia began work in 2006. Its jurisdiction was limited to senior leaders of Democratic Kampuchea and those considered most responsible for crimes committed between 17 April 1975 and 6 January 1979. The court convicted S-21 chief Kaing Guek Eav, known as Duch, as well as senior leaders Nuon Chea and Khieu Samphan. Other defendants died before proceedings concluded or were found unfit for trial.

The number of convictions was small relative to the scale of the crimes. Some Cambodians regarded the tribunal as a late but important acknowledgement of what had happened. Others criticised its duration, cost, limited group of defendants and political difficulties. Even so, the proceedings created a detailed evidential record and formally documented many mechanisms of the regime.

The consequences cannot be measured only by the number of deaths. Cambodia lost a vast body of trained professionals. Education, healthcare, religious institutions and family networks were shattered. Survivors returned to cities where homes had been looted, records had disappeared and relatives were missing. Many children grew up without parents, while families spent decades trying to discover what had happened to loved ones.

Trauma passed to later generations through silence, fear, poverty and unresolved family histories. At the same time, Cambodia developed its own culture of remembrance. Tuol Sleng, Choeung Ek, provincial memorials, school programmes and the archives of the Documentation Center of Cambodia help present the past not only as a national tragedy but as a question of responsibility, justice and prevention.

How to speak about this history today

The Khmer Rouge period is essential to understanding modern Cambodia, but the country should not be reduced to four years of terror. Cambodian civilisation existed long before Pol Pot and continued after his fall. International visitors should be especially careful not to confuse *Khmer* with *Khmer Rouge*. The first refers to Cambodia's majority people and language; the second to a specific radical political movement.

It is also misleading to treat every former low-ranking participant as equally responsible. The movement included committed cadres, recruited teenagers, mobilised villagers, people acting under threat and individuals who were later caught in purges themselves. This does not remove personal responsibility for crimes, but it helps explain why post-war Cambodian society could not be divided neatly into wholly innocent and wholly guilty groups.

Visits to Tuol Sleng or Choeung Ek provide access to documents, photographs and testimony that a short historical account cannot reproduce. These are memorial sites, not ordinary tourist attractions or backdrops for dramatic photographs. Behind every prison number was a person, and many Cambodian families remain directly connected to the period.

The most useful question is not simply how one dictator compelled an entire country to obey. A more revealing question is how war, destroyed institutions, radical ideology, secret party structures, dehumanisation and fear gradually made mass violence part of government. That broader view does not lessen the responsibility of Pol Pot and other senior leaders. It explains why the catastrophe became possible and why its memory matters far beyond Cambodia.

The essential conclusion

From 17 April 1975 until 7 January 1979, the Khmer Rouge ruled Cambodia as Democratic Kampuchea. The regime forcibly transferred the population, imposed collective labour and removed people's ability to control their own lives. Its attempt to create a radical agrarian society produced mass starvation, family separation, religious suppression, executions, ethnic persecution and internal purges.

Pol Pot was the principal leader and symbol of the regime, but the crimes were carried out through a wide administrative and security system. The regime fell after war with Vietnam, yet armed conflict continued for another two decades and formal justice arrived only much later.

The central lesson is that mass violence did not begin with one isolated order and cannot be explained only by the pathology of one individual. It became possible when institutions were destroyed, whole categories of people were declared suspect, social ties were broken and disagreement itself was treated as proof of guilt.

Sources

1. Extraordinary Chambers in the Courts of Cambodia — historical background, jurisdictional materials and the summary of judgement in Case 002/02, 2018–2024. Checked 25 July 2026.
2. United States Holocaust Memorial Museum — materials on Cambodia in 1975–1979, the origins of the Khmer Rouge, forced labour, collectivisation and S-21. Checked 25 July 2026.
3. Documentation Center of Cambodia — Khamboly Dy, *A History of Democratic Kampuchea (1975–1979)*. Educational and research edition. Checked 25 July 2026.
4. Tuol Sleng Genocide Museum — institutional history and archival materials relating to S-21. Checked 25 July 2026.

Frequently asked

Are the Khmer Rouge and the Khmer people the same?

No. The Khmer Rouge was a political and military movement, while Khmer refers to Cambodia's majority ethnic group and language. Most victims of the regime were also Khmer.

Why did the Khmer Rouge evacuate Phnom Penh?

The leadership wanted to dismantle urban life and place the population under the control of rural collectives. Claims that the evacuation was temporary or necessary because of bombing concealed the scale of the forced transfer.

Was Pol Pot convicted by an international tribunal?

No. Pol Pot died in 1998, before the Extraordinary Chambers in the Courts of Cambodia began work, and was never tried by the internationally supported tribunal.

Why are the events of 1975–1979 called genocide?

The term is widely used for the Cambodian catastrophe as a whole, but genocide has a narrower legal definition. The tribunal found genocide against particular ethnic and religious groups alongside extensive crimes against humanity.