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  • Abbie Harby

The Cambodian Genocide, Explained

Updated: Dec 4, 2021

1975 was the year the Vietnam War ended, Margaret Thatcher defeated Edward Heath in the Conservative Party leadership election, NASA launches the first joint USA and Soviet Union space flight, and the blockbuster film Jaws is released. However, it was also the year that one of the worst genocides in history began. This cheat sheet will look at the nitty gritty of what happened in Cambodia in the 1970s.


Before genocide even began, Cambodia, a land in which major income inequality ruled, faced 8 years of civil war. The Cambodian monarchy, and later the Cambodian Republic and its Allies (including the US), was standing against the Communists (supported by neighbouring Vietcong). At the time, the monarchy was considered corrupt and ineffective making the nation a breeding ground for both left- and right-wing opposition groups (Khmer Rouge is a name to remember). This was the militant wing which developed from the Cambodian Communist Party in the 1960s and was based in the jungles and mountains of the country.

In 1970, a right-wing military coup put an end to Prince Norodom Sihanouk’s reign as head of state. Consequently, Khmer Rouge joined a coalition with Prince Sihanouk which saw support for them rapidly increase. With the Vietnam War as the backdrop to years of civil war, the US was bombing areas of Cambodia and increasing support for Lon Nol in order to successfully install a pro-West leader of Cambodia, while Khmer Rouge took increasing control of the countryside between 1970 and 1975.

Khmer Rouge eventually took control of the capital, Phnom Penh, by toppling a right-wing government supported by the U.S and therefore the whole nation by 1975.

Khmer Rouge and Pol Pot

Also known as Brother Number One, Pol Pot was born into a farming family in Cambodia in 1925. He then studied in France where he joined communist groups before returning to his homeland in 1953 and working with underground communist groups. Pot pulled his ideas from a mixing pot of Stalinist and Maoist ideas with a focus on agrarian farming society and he wanted to see society return to how it was in the Middle Ages.

Khmer Rouge believed that Cambodians had been contaminated by the outside world (particularly by the capitalist West) and their aim was to create a society in which everyone worked for the common good. Pol Pot wanted Cambodia to start again at “Year Zero” and he began transforming the nation which was re-named Kampchea.

In order to achieve this, Cambodians were cut off from the rest of the world, cities were emptied, people were placed in communes, and they carried out “re-education” programmes to promote this collective lifestyle. Anyone who refused re-education was killed or sent to the infamous prison camp Tuol Sleng Centre, known as S-21. Money, private property and religion were all abolished.

Every citizen was categorised into groups that reflected how much trust and respect Khmer Rouge had for them; the most trusted being called “old citizens”. In contrast, “new citizens” were those from the cities and supporters of the West who could move up to being labelled “deportees”, then “candidates” and finally “full rights citizens”. The sad truth was that most citizens never actually moved up the ranks.

Cambodian genocide under Khmer Rouge 1970s

The reality

Deaths from starvation and disease were all too common during this period. Poor management of the economy and the establishment of labour brigades based on age and gender all led to shortages of food and medicine. These practices meant that families were constantly split up.

Khmer Rouge targeted, persecuted and executed numerous people over the 4 years that the regime was in power. They set up specially developed centres to accommodate such actions, the most well-known being the S-21 jail. Some estimates say that as many as 17,000 men, women and children were imprisoned here over Khmer Rouge’s 4 years of power.

  • The group predominantly targeted was the ethnic Vietnamese and Cham Muslims – as many as 500,000 Cham Muslims or 70% of the total Cham population was wiped out.

  • Religious groups, such as Christians and Buddhists were repressed.

  • Intellectuals and educated members of the middle class (particularly doctors, lawyers, journalists, artists, members of the clergy and students), anyone who wore glasses or knew a foreign language were tortured and executed.

  • In total these mass killings ended up eliminating 1/5 of Cambodia’s population.

  • The exact number of victims of the Cambodian genocide is hard to define. Although the Cambodians kept records of prisoners and executions, when Vietnam (Cambodia’s enemy) invaded and released the records, it is possible that the numbers could have been exaggerated.

The end of Khmer Rouge

Following numerous violent confrontations on the border with Vietnam, in 1979 Khmer Rouge was overthrown by Vietnamese troops who then established a pro-Vietnam decade-long occupation of Cambodia.

Despite losing power, Khmer Rouge continued to receive support from several western countries, including assistance from the US who wished to challenge Vietnamese authority in Cambodia. Khmer Rouge even held onto their seat in the U.N General Assembly and was recognised as the only legitimate representative of the nation.

Pol Pot also avoided capture and held onto a level of power for a further 20 years. Other members of Khmer Rouge who were in positions of power retreated to remote areas where they remained active for some time before their power diminished.


As mentioned in our Cheat Sheet on Genocide, the definition of the term is somewhat foggy. Consequently, some scholars deny that the events in Cambodia qualify as genocide under the United Nations Convention. They would claim that there is no proof of intent to wipe out one specific ethnic or religious group and instead many have stated that it could be termed an “auto-genocide”; the persecution and executions occurred across the whole of society, rather than just targeting one group.


In 1992, the UN’s Transitional Authority in Cambodia (UNTAC) employed Khmer Rouge and Pol Pot as necessary partners to bring peace to Cambodia.

UNTAC’s other goal was to put Pol Pot and other senior leaders on trial. Several leaders were tried in absentia by the Extraordinary Chambers in the Courts of Cambodia, or the Khmer Rouge Tribunal, following the Vietnamese takeover in 1979. In 1997 Pol Pot was denounced and sentenced to house arrest by his comrades, but before he could properly be put on trial, Pot died in 1998.

In 2009, the UN set up a tribunal to try any surviving leaders of Khmer Rouge. So far, five members have been indicted, one died during trial, while another has been deemed unfit for trial, meaning only three have been sentenced: Kaing Guek Eav was jailed for life in 2021 for running the Tuol Sleng (S-21) prison; Nuon Chea (Brother Number 2 to Pol Pot) and Khieu Samphan (Khmer Rouge’s head of state) were jailed for life for crimes against humanity. In 2018, they were also found guilty of genocide over the attempted extermination of the Cham and Vietnamese minorities.

Due to the fact that the Khmer Rouge trials are so controversial in Cambodia because of their cost and ineffectiveness, this is the first and only genocide conviction against the Khmer Rouge.

The courts are also responsible for providing victim support and documenting the crimes and there is no deadline for the court to stop its operations.

Cambodia today

Scars of Pol Pot’s brutal regime and the civil war which continued into the 1990s still remain engrained in the country’s memory.

Many former Khmer Rouge members are still in power today, including Hun Sen who, having been Cambodia’s Prime Minister since 1985, is now the longest-serving prime minister in the world. Cambodia has never been fully democratic; when Hun Sen was re-elected in 2018, TIME reported that the voting has been criticised for a major crackdown on opposition and attacks on the press.

Politically, Khmer Rouge’s legacy is obvious as the collapse of that regime is central to the existence of the ruling government with the CPP positioning itself as the saviours of Cambodia who saved the nation.

According to the journalist and historian Sebastian Strangio, the government has such tight control over information in Cambodia that it has prevented even “some kind of objective understanding of what happened”. Consequently, it will take even longer until Cambodia will fully come to terms with its history. Strangio says “it will take the passing of this political generation” before people will be able to talk about the past in an open and honest way.

Many places connected with this extremely difficult history are now popular tourist destinations; for example, the Tuol-Seng museum is located in the former S-21 prison, the killing fields, signs marking mass graves. The arts have also begun to tackle the subject, including major film productions and popular songs breaching the topic of the Cambodian genocide.

For more resources on this topic, head to our dedicated Racism, Islamophobia and Antisemitism section.

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