After the March 1970 coup that installed Lon Nol, Cambodian forces and civilians carried out killings of ethnic Vietnamese residents, most notoriously at Prasaut and along the Mekong where bodies were floated downriver, and the government interned and then expelled much of the community; South Vietnamese and international accounts put the number repatriated at 200,000-300,000 and the dead in the thousands. Under Democratic Kampuchea the remaining Vietnamese were expelled in 1975-76 and those who stayed, along with Khmer people with Vietnamese spouses, were systematically killed. The Extraordinary Chambers in the Courts of Cambodia found in Case 002/02 that the Khmer Rouge committed genocide against the ethnic Vietnamese of Cambodia, convicting Nuon Chea and Khieu Samphan in November 2018; the conviction was upheld on appeal in 2022. The community was effectively eliminated from Cambodia by 1979, and those who returned afterwards have faced continuing statelessness and periodic violence.
The Lon Nol republic and then the Khmer Rouge expelled and killed Cambodia's ethnic Vietnamese population
Estimates for 1970 range from about 250,000 to 450,000, with 400,000-450,000 the figure most often cited from French colonial and Sihanouk-era counts. Roughly 200,000-300,000 were expelled to South Vietnam in 1970, and of the tens of thousands who remained or returned, Khmer Rouge policy after 1975 aimed at total removal; the 1980s censuses recorded only a small remnant before postwar return migration.
The range covers those killed in the 1970 pogroms, put in the low thousands by contemporary press and diplomatic reporting, and those killed under Democratic Kampuchea, estimated by the Documentation Center of Cambodia and accepted in outline by the Extraordinary Chambers at up to about 20,000 of the roughly 20,000-30,000 Vietnamese thought to have remained after the 1975-76 expulsions. The uncertainty is driven by the unknown size of the residual community.
The Extraordinary Chambers in the Courts of Cambodia and the Documentation Center of Cambodia documented mass killing, executions and the internment of ethnic Vietnamese, and their stripping of status and expulsion by both governments.
Cambodia, Vietnam