(source)
The Killing Fields are a number of sites in Cambodia where large numbers of people were killed and buried by the Khmer Rouge regime, during its rule of the country from 1975 to 1979. … Analysis of 20,000 mass grave sites by … indicate at least 1,386,734 victims. Estimates of the total number of deaths resulting from Khmer Rouge policies, including disease and starvation, range from 1.7 to 2.5 million out of a population of around 8 million. (source)
More on genocide here and here. More iconic images of human rights violations are here.

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