During the Khmer Rouge rule of the country from 1975 to 1979, immediately after the end of the Vietnam war, over 200,000 people were executed and buried in the killing fields just outside Phnom Penh, the captial of Cambodia. The total deaths of the regime is estimated to be 1.4-2.2million (out of the 7 million population) mostly due to starvation and disease.
In order to save on ammunition, many of the executions were done with sharpened sticks, axes, etc and victims put in mass graves of up to 200 people, but typically around the 100 mark.
The victims were undug in 1980 after Vietnam took the Khmer Rouge regime down out of the mass graves and a memorial stupa was built with glass windows and filled with the skulls of the victims to release their souls after their brutal death. The holes from the graves being dug up are still present there today.