Pol Pot
"Pol Pot transformed Cambodia into a one-party state which he called Democratic Kampuchea. Seeking to create an agrarian socialist society that he believed would evolve into a communist society, Pol Pot's government forcibly relocated the urban population to the countryside and forced it to work on collective farms. Pursuing complete egalitarianism, money was abolished and all citizens were forced to wear the same black clothing. Mass killings of perceived government opponents, coupled with malnutrition and poor medical care, killed between 1.5 and 2 million people, approximately a quarter of Cambodia's population, a process which was later termed the Cambodian genocide."1
You can learn some more on Wikipedia, but I encourage you to broaden your search and get other points of view.