
Kampuchea, officially from 5 January 1976 Democratic Kampuchea, also described as the Genocidal Regime, was the Cambodian state under a one-party Marxist-Leninist totalitarian dictatorship that existed between 1975 and 1979. It was controlled by the Khmer Rouge (KR), the name popularly given to the followers of the Communist Party of Kampuchea (CPK), and was founded when KR forces defeated the Khmer Republic of Lon Nol in 1975.
The Cambodian genocide was the systematic persecution and killing of Cambodians by the Khmer Rouge under the leadership of Pol Pot, who radically pushed Cambodia towards communism. It resulted in the deaths of 1.5 to 2 million people from 1975 to 1979, nearly a quarter of Cambodia's 1975 population.

The Cambodian–Vietnamese War, known in Vietnam as the Counter-offensive on the Southwestern border, and by Cambodian nationalists as the Vietnamese invasion of Cambodia, was an armed conflict between Democratic Kampuchea, controlled by the Khmer Rouge, and the Socialist Republic of Vietnam. The war began with repeated attacks by the Kampuchean Revolutionary Army on the southwestern border of Vietnam, particularly the Ba Chuc massacre which resulted in the deaths of over 3,000 Vietnamese civilians. On 25 December 1978, Vietnam launched a full-scale invasion of Kampuchea, and subsequently occupied the country and removed the government of the Communist Party of Kampuchea from power.

The Communist Party of Kampuchea, also known as the Khmer Communist Party was a communist party in Cambodia. Its leader was Pol Pot and its followers were generally known as Khmer Rouge. Originally founded in 1951, the party was split into pro-Chinese and pro-Soviet factions, as a result of the Sino–Soviet split. As such, it claimed 30 September 1960 as its founding date, then as the Workers' Party of Kampuchea before being renamed the Communist Party in 1966. The party was underground for most of its existence and took power in the country in April 1975 and established the state known as Democratic Kampuchea. The party lost power in 1979 with the establishment of the People's Republic of Kampuchea by leftists who were dissatisfied by the Pol Pot regime and by the intervention of Vietnamese military forces after a period of mass killing. The party was officially dissolved in 1981, with the Party of Democratic Kampuchea claiming its legacy.

"Dap Prampi Mesa Moha Chokchey" was the national anthem of Democratic Kampuchea from at least January 1976. Although the anthem may have been in use in the "liberated zone" much earlier, it was proclaimed the national anthem in article 18 of the Constitution of Kampuchea which was promulgated on 5 January 1976. Supposedly, the Khmer Rouge and/or Pol Pot himself wrote the piece, but its origin remains unknown.

The Deputy Presidents of the State Presidium of Kampuchea were deputy heads of state of Democratic Kampuchea 1976 - 1978.

The flag of Democratic Kampuchea consisted of the golden Angkor Wat in the red background. It was adopted on 5 January 1976 during Khmer Rouge rule under Cambodia.

The Royal Government of the National Union of Kampuchea was a government-in-exile of Cambodia, based in Beijing, that was in existence between 1970 and 1976, and was briefly in control of the country starting in 1975.

The Kampuchean Revolutionary Army was the Armed Forces of Democratic Kampuchea.