Communist movement in Cambodia (Kampuchea) formed in the 1960s.
Controlling the country between 1974 and 1978, the Khmer Rouge was responsible for mass deportations and executions under the leadership of Pol Pot. They formed the largest opposition group to the US-backed regime led by Lon Nol from 1970 to 1975.
By 1974 they controlled the countryside, and in 1975 captured the capital, Phnom Penh.
Initially former prime minister Prince Sihanouk was installed as head of state, but internal disagreements led to the creation of the Pol Pot government in 1976.
From 1978, when Vietnam invaded the country, the Khmer Rouge conducted a guerrilla campaign against the Vietnamese forces. Pol Pot retired as military leader in 1985 and was succeeded by the more moderate Khieu Samphan.
After the withdrawal of Vietnamese forces in 1989, the Khmer Rouge continued its warfare against the Vietnamese-backed government.
A UN-brokered peace treaty in October 1991 between Cambodia’s four warring factions gave the Khmer Rouge its share of representation in the ruling Supreme National Council, but failed to win a renunciation of the guerrillas’ goal of regaining domination of Cambodia.
Fighting between Khmer Rouge and government forces continued into 1994.
Two Khmer Rouge leaders – Khieu Samphan and Nuon Chea – apologised in December 1998 for the genocide of the 1970s, although they refused to accept responsibility for the slaughter of about two million of their countrymen.
The two men surrendered to Prime Minister Hun Sen after he pledged they would not face trial for crimes against humanity. By 1999, most members had surrendered or been captured.
In December 1999, Ta Mok and the remaining leaders surrendered, and the Khmer Rouge effectively ceased to exist.
Most of the surviving Khmer Rouge leaders live in the Pailin area or are hidden in Phnom Penh. Trials continue against former Khmer Rouge members, with charges of genocide and crimes against humanity.
After claiming to feel great remorse for his part in Khmer Rouge atrocities, Kaing Guek Eav (head of a torture centre from which 16,000 men, women and children were sent to their deaths) surprised the court in his genocide trial on 27 November 2009 with a plea for his freedom.
On 26 July 2010 he was convicted and sentenced – to only thirty years.