It's hard to believe that the Khmer Rouge ever existed, and that they were not a bad dream; but exist they did, from 1951 to 1999. The extremist wing of the Kampuchean Communist Party, led by electrician and carpenter Pol Pot, the Khmer Rouge were a kind of dadaist, left-wing political party who, with the best will in the world, embarked on a program of national self-genocide which was both horrifying and irrational. Born the chaos of Nixon's invasion and bombing of Cambodia, the Khmer Rouge slaughtered almost a third of their country's entire population, because of an idea.

From 1970 to 1973 the Cambodians had been bombed and battered by the North Vietnamese army and the USAF with enormous loss of life; to the average Cambodian, the Khmer Rouge appeared to be the lesser of several evils. By 1975 they had gained control of the country, at which point things went downhill rapidly. The capital city, Phnom Penh, fell in that year, which was ominously dubbed 'Year Zero' by Pot.

Hoping to make John Lennon's 'Imagine' a reality, the Khmer Rogue set out to establish an agricultural, communist utopia where there was no property, no heaven, and no hell. And no Cambodians, for between 1975 and 1978 almost two million were executed, starved, overworked, or allowed to die of disease - this, in a country with a contemporary population of seven million. To be suspected of intellectualism was the ultimate crime; those who wore glasses, or who were overweight or well-spoken were executed en masse, whilst the urban population was forcibly evacuated to the countryside in order to take up the simple life of peasantry. Those who did not work hard enough were killed; those who wasted time grieving for the dead were killed; it was all rather like the Twilight Zone episode 'It's a Good Life', with the psychic kid wishing people into a cornfield.

Neighbouring Vietnam was understandably worried by this, and as a result of Pol Pot's sabre-rattling and insane over-estimation of Cambodia's military strength, Vietnam invaded Cambodia on Christmas Day, 1978. Within a few months, the Khmer Rouge were deposed, and replaced with a government made of ex-Khmer Rogue officials who were worried that Pol Pot had been on the verge of executing them. After this, the Khmer Rouge devolved from being a major political force, to being a dwindling guerilla group - one which finally tore itself apart in 1999. That the Khmer Rouge could kill one-third of their own countrymen does not bode well for humanity; that political ideals of all persuasion seem to have led to unspeakable horror regularly throughout the 20th century suggests that people should not be let loose with ideas.

Pol Pot himself died peacefully in 1998, at the age of 73, whilst the vast majority of the Khmer Rouge's senior officers are still alive and free.