This document provides background information on Cambodia and the rise of the Khmer Rouge regime from 1975-1979. It discusses Cambodia's history from the Angkor Empire to French colonization. In the 1960s-1970s, as the Vietnam War escalated, King Sihanouk allowed Vietnamese communists to operate in Cambodia, angering some. In 1970, Sihanouk was deposed while abroad and the US-backed Khmer Republic took over. US bombing of Cambodia strengthened the Khmer Rouge. When they took Phnom Penh in 1975, the Khmer Rouge forcibly evacuated cities and eventually killed an estimated 1.7-2 million Cambodians through executions, starvation, and overwork in an attempt to create an