The brutal acts of the Khmer Rouge regime led by Pol Pot were responsible for the deaths of approximately 2 million Cambodians.
The regime had attempted to turn the country into a classless society, where everyone was equal and to work as a farmer. Anyone who showed dissent could be seen as “conspiring against the regime” and be imprisoned. Even people who simply wore glasses were considered “intellectuals” - in this manner showing dissent - and found themselves arrested. Prisons were overcrowded as a result.
One way the regime dealt with overcrowding in the prisons was through mass executions. These skulls are the remains of people who were buried alive or bludgeoned to death by the Khmer Rouge in the Choeung Ek Killing Fields, south of the capital Phnom Penh.