The Khmer Rouge, under its Marxist-influenced tyrannical leader, Pol Pot, only ruled for 4 years from 1975-1979 but embarked on a repressive totalitarian regime, which led to deaths estimated between 1.7-2 million. During that time, any opposition, real or imagined, was brutally crushed, and a bloody genocide resulted. Cambodia, under the Khmer Rouge, was known as Democratic Kampuchea.
When the Khmer Rouge marched into Phnom Penh in 1975, after several years of internal civil war, they executed all Lon Nol senior government and military officials within days. Upon this takeover, they undertook a sharply radical and brutal transformation of a society- to transform Cambodia into a peasant-dominated agrarian co-operative.
All of Phnom Penh was evacuated, including the hospitals, and marched into the countryside to work as slaves. Clock were turned back to year zero, the currency abolished, postal services discontinued and all ties with the outside, but for a fortnightly flight into Beijing, were cut. The Khmer Rouge turned Cambodia into a prison without walls.
The actual number of deaths are not known and while many died from disease, hunger, and slave labor, hundreds of thousands – many of them Cambodia's skilled and educated– were executed in "killing fields". Some have speculated that the US carpet-bombing of Cambodia, especially in 1973, may have driven the rural peasants to the side of the Khmer Rouge and hardened the attitudes of the recruits, contributing to their later brutality.
After Phnom Penh, the cleansing program was extended to the outer regions in a purge against anti Pol Pot factions. The most brutal and bloodiest occurred against the independent and more moderate Eastern Zone group which were pro-Vietnam. Hundreds of Eastern Zone leaders were executed, sparking a civil war, and many leaders fled to Vietnam. They would form the core of a government that would be later installed by the Vietnamese in Phnom Penh in 1979.
As more and more moderates were killed by the cadres in their unmistakable uniforms of black with checkered scarves, even the peasants, who had earlier supported the revolutionaries, could no longer follow such madness.
Khmer Rouge leader Pol Pot had many names – born Saloth Sar, he was called Pouk, Hay, Grand Uncle, Brother No.1 and later as "99" and Phem. He was the man responsible for the genocide, but remained in the shadows until 1976. As a young student in Paris, he was introduced to Marxist ideals that were later distorted to support his murderous regime. When the Vietnamese tanks rolled into Phnom Penh in early 1979, Pol Pot ran into the jungle between Cambodia and Thailand and continued his violent warfare until his death in 1998.