I will again preface this with I am not a professional historian so what is conveyed bellow is what I understand to be correct. If you know more and would like to educate me further, please reach out so I can correct any misinformation. Thanks.
Something which is known by some, but largely forgotten by the international community, is the atrocities which occurred in Cambodia under the reign of the Khmer Rouge in the late 1970’s. Building off the countries anger from the aggressive bombings throughout the country by the US during the second Indochine war (Vietnam War), the communist fanatic Pol Pot was able to raise a militia and take control of the country. Pol Pot had been raised by a farming family in Cambodia, and got an education in the capital while living with his brother who worked in the royal palace. Later he moved to France, where he furthered his education, and became a strong following member of the French communist party. Upon his return to Cambodia he grew in the ranks of the Communist Party of Kampuchea and eventually headed the Khmer Rouge. The Khmer Rouge militia overran Phnom Penh as well as most other major cities later in 1975, and the people welcomed them as a liberation force. Pol Pot wasted no time and quickly drained all populated areas of people and within three days there were fewer than a couple hundred people in the capital city. He told the people it was to protect them from any further air raids, but little did they know it was the beginning of a systematic plan which ended up killing more than a third of the country less than four years. Pol Pot claimed they were giving the country back the the famers and peasants and moving people out of the cities and having them begin working in the fields would increase the prosperity of the country. However Pol Pot and the high members of the Khmer Rouge deeply distrusted any intellectuals thinking they might turn agains this new power. Doctors, teachers, skilled professionals, politicians, were rounded up and taken to prisons where they couldn’t rebel. These prisons were particularly dark. Here prisoners were not just held, but tortured repeatedly until they wrote forced confessions claiming they had been plotting against the Khmer Rouge. Once they confessed they were taken out of prisons and put to death for their crimes against the Ankor. The Khmer Rouge had abolished any religion and replaced it with worship to the Ankor, the high powers in Khmer Rouge. As such many monks and religious figures were also brought to the prisons. In just a few months these prisons and killing fields sprouted up all over the country and a systematic culling of the population began.
One such prison, S-21, one of the largest in Cambodia, was located right in Phnom Penh and has been converted to a museum to honor those lost and to teach the horrific acts of the Khmer Rouge so they will never be forgotten. A primary school before the Khmer Rouge take over, class rooms were converted to holding cells, which would contain 50+ prisoners shackled to the floor. Other class rooms were converted to the torture chambers where “interrogators” would torture prisoners until they confessed and were sent to the killing fields. The museum explains the horrific conditions people were held in, and the even worse method of torture that were used. Everything from beating, to waterboarding, to being hung upside down till the blood in your head caused you to pass out, only to be dunked in a vat of rotten food and human feces to cause you to come back to consciousness. Interrogators were frequently children who were brainwashed by the Khmer Rouge head of prisons, Duch. While they were torturing prisoners, the Khmer Rouge had a very backwards control over their people. Saying they were rooting out traitors, no one was allowed to be killed until they had signed a written confession of their crimes against the Ankor. Interrogators could themselves become prisoners if they crossed a line and accidentally killed their victims in the process of getting a confession. As the Khmer Rouge rule continued, prisoners went from just intellectuals and religious figures to just about anyone the Ankor deemed “dangerous”. These “dangerous individuals” included children, simple farmers (the people Pol Pot said he was fighting for) and even a few unlucky foreigners who stumbled into Cambodian borders during the Khmer Rouge reign. Believing they were actually rooting out enemies of the state, these prisons kept detailed reports on all the prisoners who came through. In the four years of their reign, 21,000 prisoners went through S-21 alone. Only 4 survived.
Walking through this tainted place you can feel the destructive power the Khmer Rouge had over the county. Pictures from the prison’s records adorn the walls as you walk along and listen to an audio tour that tells the story of the Khmer Rouge and what happened at the prisons. To this day people still come to sort through the records recovered to see if loved ones they had been separated from had become prisoners and later victims of the genocide. Not for the feint of heart, the audio tour takes you through a journey showing the destruction this place had, not only on the prisoners, but their families, and even the people who worked there.

After visiting S-21 we continued on the depressing tour 15km out of the city to Choeng Ek, commonly known as the killing fields. One of many which accompanied the numerous torture prisons spread across the country these were the sights were the “confessed” prisoners were taken to be executed. Another audio tour walks you through the place where the 21,000 prisoners of S-21 were murdered. Depressions in the ground mark were mass graves were dug and a practically constant stream of people were executed for four years straight. Deeming bullets too valuable, the Khmer Rouge found horrific ways to kill victims. Most involving blunt force by metal rods, machetes, tilling hoes, hard sticks, and just about whatever else they could get there hands on. Prisoners were typically brought out at night by the truckload so no one knew where they were going. They were blind folded and forced into sheds, not knowing their fate listening to the sound of loud diesel generators and blasting propaganda music to drown out the cries of those ahead of them. Soon after the fall of the Khmer Rouge in 1979 these sights were discovered and many of the remains were exhumed and cataloged, however as you walk around the grounds new bits of bone and clothes regularly make their way to the surface and can be seen across the ground.

One of the hardest parts for me was “the killing tree”. Babies would be stripped from their mothers arms and taken to this tree, where their heads were smashed against the hard bark and they were thrown into the mass graves beside it. If S-21 was hard, the killing fields themselves hold an even deeper level of eerie dark power. The exact numbers are still not known but somewhere between 1.7-2.5 million people were killed this way between 1975-1979.
The atrocities of the Khmer Rouge didn’t end with just their direct murder of a significant portion of the country. Further losses of life occurred from the forced labor when Pol Pot demanded rice production be tripled in the country. People of all ages, many of whom had no idea what they were doing were sent to work in the rice paddies. However much of this increased production was sold to China to purchase weapons for the Khmer Rouge fighters, leaving 10s to 100s of thousands of more people to die of starvation.
The Khmer Rouge finally fell from power in 1979 when they were run out of the capital by Cambodian rebels backed strongly by Vietnamese troops. However many of the heads of the Khmer Rouge lived on in Cambodia, including Pol Pot who lived until 1993 when he died in his home on the Thai border. Following the fall of the Khmer Rouge the Cambodian Peoples Party was formed with he help of the Vietnamese government. Yet somehow, even after the killing fields were discovered and the atrocities of the Khmer Rouge were known the UN still recognized the Khmer Rouge as the ruling party of Cambodia until 1989! Having recently lost the Vietnam War the US refused to back a Vietnamese aided communist government so instead they recognized known murders for almost 10 years!