Phnom Penh in the context of "Cambodian People's Party"

Cambodia, officially the Kingdom of Cambodia, is a country in Mainland Southeast Asia. It is bordered by Thailand to the northwest, Laos to the north, and Vietnam to the east, and has a coastline along the Gulf of Thailand in the southwest. It spans an area of 181,035 square kilometres (69,898 square miles), dominated by a low-lying plain and the confluence of the Mekong river and Tonlé Sap, Southeast Asia's largest lake. It is dominated by a tropical climate. Cambodia has a population of about 17 million people, the majority of which are ethnically Khmer. Its capital and most populous city is Phnom Penh, followed by Siem Reap and Battambang.

In 802 AD, Jayavarman II declared himself king, uniting the warring Khmer princes of Chenla under the name "Kambuja". This marked the beginning of the Khmer Empire. The Indianised kingdom facilitated the spread of first Hinduism and then Buddhism to Southeast Asia and undertook religious infrastructural projects throughout the region, the most famous of which is Angkor Wat. In the 15th century, it began a decline in power until, in 1863, Cambodia became a French protectorate. Following Japanese occupation during World War II, Cambodia declared independence from France in 1953. The Vietnam War embroiled the country in civil war during the 1960s, culminating in a 1970 coup which installed the US-aligned Khmer Republic and the takeover of the communist Khmer Rouge in 1975. The Khmer Rouge ruled the country and carried out the Cambodian genocide from 1975 until 1979, until they were ousted during the Cambodian–Vietnamese War. Peace was restored by the 1991 Paris Peace Accords and subsequent United Nations peacekeeping mission, establishing a new constitution, holding the 1993 general election, and ending long-term insurgencies. The 1997 coup d'état consolidated power under Prime Minister Hun Sen and the Cambodian People's Party (CPP).

Pol Pot (born Saloth Sâr; 25 May 1925 – 15 April 1998) was a Cambodian politician, revolutionary, and dictator who ruled the communist state of Democratic Kampuchea from 1975 until his overthrow in 1979. During his reign, his administration oversaw mass atrocities and he is widely believed to be one of the most brutal despots in modern world history. Ideologically a Maoist and Khmer ethnonationalist, Pot was a leader of Cambodia's Communist movement, known as the Khmer Rouge, from 1963 to 1997. He served as General Secretary of the Communist Party of Kampuchea from 1963 to 1981, during which Cambodia was converted into a one-party state. Between 1975 and 1979, the Khmer Rouge perpetrated the Cambodian genocide, in which an estimated 1.5–2 million people died—approximately one-quarter of the country's pre-genocide population. In December 1978, Vietnam invaded Cambodia to remove the Khmer Rouge from power. Within two weeks Vietnamese forces occupied most of the country, ending the genocide and establishing a new Cambodian government, with the Khmer Rouge restricted to the rural hinterlands in the western part of the country.

Born to a prosperous farmer in Prek Sbauv, French Cambodia, Pol Pot was educated at some of Cambodia's most elite schools. Arriving in Paris in October 1949 on an academic scholarship, he later joined the French Communist Party in 1951 while studying at École française de radioélectricité. Returning to Cambodia in 1953, he involved himself in the Khmer Viet Minh organisation and its guerrilla war against King Norodom Sihanouk's newly independent government. Following the Khmer Viet Minh's 1954 retreat into North Vietnam, Pol Pot returned to Phnom Penh, working as a teacher while remaining a central member of Cambodia's Marxist–Leninist movement. In 1959, he helped formalise the movement into the Kampuchean Labour Party, which was later renamed the Communist Party of Kampuchea (CPK). To avoid state repression, in 1962 he relocated to a jungle encampment and in 1963 he became the CPK's leader. In 1968, he relaunched the war against Sihanouk's government. After Lon Nol ousted Sihanouk in a 1970 coup, Pol Pot's forces sided with the deposed leader against the new government, which was bolstered by the United States military. Aided by the Viet Cong militia and North Vietnamese troops, Khmer Rouge forces advanced and controlled all of Cambodia by 1975.

The Fall of Phnom Penh was the capture of Phnom Penh, capital of the Khmer Republic (in present-day Cambodia), by the Khmer Rouge on 17 April 1975, effectively ending the Cambodian Civil War. At the beginning of the month, Phnom Penh, one of the last remaining strongholds of the Khmer Republic, was surrounded by the Khmer Rouge and totally dependent on aerial resupply through Pochentong Airport.

With a Khmer Rouge victory imminent, the United States government evacuated US nationals and allied Cambodians on 12 April. On 17 April, the Khmer Republic government evacuated the city, intending to establish a new government center close to the Thai border to continue resistance. Later that day, the last defences around Phnom Penh were overrun and the Khmer Rouge occupied Phnom Penh.

The Cambodian–Vietnamese War was an armed conflict from 1978 to 1989 between the Khmer Rouge and Vietnam, and their respective allies. It began in December 1978, with a Vietnamese invasion of Cambodia which toppled the Khmer Rouge and ended in 1989 with the withdrawal of Vietnamese forces from Cambodia. This Cold War conflict was part of the Third Indochina War and Sino-Soviet split with the Soviet Union supporting Vietnam and China supporting the Khmer Rouge.

Despite both being communist, the alliance between the Communist Party of Vietnam and the Khmer Rouge broke down after both defeated Vietnamese and Cambodian anti-communist regimes respectively in the Vietnam War. As a result, the war was preceded by years of conflict between Vietnam and the Khmer Rouge, led by Pol Pot, when the Khmer Rouge ruled Democratic Kampuchea repeatedly invaded Vietnam, including massacres by the Khmer Rouge, notably the Ba Chúc massacre of over 3,000 Vietnamese civilians in April 1978. On 21 December 1978, the Vietnamese launched a limited offensive towards the town of Kratie. On 23 December 1978, 10 out of 19 divisions of the Khmer Rouge's Kampuchea Revolutionary Army opened fire along the border with Vietnam with the goal of invading the southwestern border provinces of Đồng Tháp, An Giang and Kiên Giang. On 25 December 1978, Vietnam supported Cambodian dissidents in exile and launched a full-scale invasion of Kampuchea, occupying the country in two weeks, capturing the capital Phnom Penh, and removing the Khmer Rouge government of the Communist Party of Kampuchea from power. In doing so, Vietnam put an ultimate stop to the Cambodian genocide which had killed between 1.2 and 2.8 million people or between 13 and 30 percent of the country's population since 1975. However, the Khmer Rouge regime maintained its membership in the United Nations and the war isolated Vietnam from the international community except the Eastern Bloc. The Vietnamese occupation caused discontent among Cambodians.

The French School of the Far East (French: École Française d'Extrême-Orient, pronounced [ekɔl fʁɑ̃sɛːz dɛkstʁɛm ɔʁjɑ̃]; also translated as The French School of Asian Studies), abbreviated EFEO, is an associated college of PSL University dedicated to the study of Asian societies. It was founded on 20 January 1900 with headquarters in Hanoi in what was then Tonkin protectorate of French Indochina. After the independence of Vietnam, its headquarters were transferred to Phnom Penh in 1957, and subsequently to Paris in 1975. Its main fields of research are archaeology, philology and the study of modern Asian societies. Since 1907, the EFEO has been in charge of conservation work at the archeological site of Angkor.

Paul Mus was a member of EFEO since 1927, and "returned to Hanoi in 1927 as a secretary and librarian with the Research Institute of the French School of the Far East until 1940."

Kamakura, Home of the Samurai (武家の古都・鎌倉, Buke no koto・Kamakura) is a grouping of historic sites concentrated in and around the Japanese city of Kamakura, near Tokyo. The city gave its name to the Kamakura shogunate which governed the country during the Kamakura period (1185-1333). In 1992 the monuments were submitted jointly for inscription on the UNESCO World Heritage List under criteria i, ii, iii, iv, and vi.

In January 2012 it was announced that the Japanese government would formally submit the Kamakura site, along with Mount Fuji, for consideration by the World Heritage Committee in 2013. ICOMOS, the advisory body for cultural World Heritage Sites, inspected the site in late 2012. The request was considered by the World Heritage Committee at its 37th session in Phnom Penh, Cambodia in September, 2013. ICOMOS recommended not inscribing the site on the List, stating that the historical aspects of the site had largely been supplanted by the modern city that grew up around it and thus the site lacked the integrity necessary to be considered. The request for World Heritage status was duly withdrawn by Japan.

On 15 June 2025, Thai Prime Minister Paetongtarn Shinawatra held a 17-minute private phone call with Cambodian Senate President and former Prime Minister Hun Sen to discuss a peaceful resolution to the 2025 Cambodian–Thai border crisis. Deputy Governor of Phnom Penh, Khleang Huot, acted as an interpreter on the call.

On 18 June 2025, a 9 minute audio recording of the call was leaked. Later that day, Hun Sen confirmed he had recorded the full conversation and posted it on his Facebook page.

The Tuol Sleng Genocide Museum (Khmer: សារមន្ទីរឧក្រិដ្ឋកម្មប្រល័យពូជសាសន៍ទួលស្លែង, romanized: Saromontir Ukredth Kamm Braly Pouchsasa Tuol Sleng), or simply Tuol Sleng (Khmer: ទួលស្លែង, Tuŏl Slêng [tuəl slaeŋ]; lit. "Hill of the Poisonous Trees" or "Strychnine Hill"), is a museum chronicling the Cambodian genocide. Located in Phnom Penh, the site is a former secondary school which was used as Security Prison 21 (S-21; Khmer: មន្ទីរស-២១) by the Khmer Rouge regime from 1975 until its fall in 1979. From 1976 to 1979, an estimated 20,000 people were imprisoned at Tuol Sleng and it was one of between 150 and 196 torture and execution centers established by the Khmer Rouge and the secret police known as the Santebal (lit. "keeper of peace"). On 26 July 2010, the Extraordinary Chambers in the Courts of Cambodia convicted the prison's chief, Kang Kek Iew, for crimes against humanity and grave breaches of the 1949 Geneva Conventions. He died in 2020 while serving a life sentence.