During the chaos of the Vietnam War, Cambodia was undergoing its own civil war. On April 17, 1975, the Maoist Communist rebels, the Khmer Rouge, overthrew the government of the Khmer Republic led by Lon Nol. The Khmer Rouge's plan was to eliminate modern society and create an agrarian utopia. The Khmer Rouge executed educated people, others who had ties to the old government or anyone who was believed to be advantaged by the old society (doctors, teachers, soldiers, actors, singers, boxers, etc.) and forced the remaining Khmer population into labor camps, in which many died of starvation and diseases, to be re-educated under the new government. Traditional martial arts were banned at this time and many boxers were executed or worked to death, which nearly caused the death of pradal serey. An estimated 1.7 million Cambodians or 21% of the population died during the Khmer Rouge regime according to the studies of the Cambodia Genocide Program of Yale University. This lasted for four years until 1979 when the Vietnamese along with ex-Khmer Rouge officers, including current prime minister Hun Sen, overthrew the Khmer Rouge. During the relative peace since the departure of the Vietnamese and the re-establishment of the Kingdom of Cambodia, the country's traditional arts were revived, including pradal serey.