Prime Minister General Lon Nol took control of the country in March 1970 when Sihanouk was abroad; he deposed Sihanouk, changed the name of the country from the Kingdom of Cambodia to the Khmer Republic, and re-established diplomatic relationships with the United States. Thus, Sihanouk joined forces with the Khmer Rouge to fight against the Lon Nol regime. The Khmer Rouge emerged victorious in the civil war for a multitude of reasons, including their alliance with Sihanouk, appealing to the peasant population, and heavy bombing carried out by U.S. planes that devastated the countryside in eastern Cambodia, which further alienated the rural population. The Khmer Rouge also received military/political aid from Northern Vietnam, and overall, the group steadily increased its military abilities.
The effects of the civil war were significant: 1/2 million deaths, with 3 million people displaced out of a total population of less than 8 million. The Khmer Rouge changed the name of the country to Democratic Kampuchea and ordered the population of Phnom Penh, the capital city, to evacuate the city and go back to their ancestral villages – even hospital patients were forced to move out. Former government officials, military commanders, educated people, professionals, merchants, and landlords were branded as enemies of the people and killed. The Khmer Rouge defrocked Buddhist monks, the most revered people in Cambodian society, forcing them to work in the fields and killing many of them, while also using Buddhist temples to store their weapons and ammunition.
Many of Khmer Rouge’s own officials were executed due to suspicions of disloyalty. Schools and colleges closed; private property, money, banks, markets, hospitals, Western medicine, and all “modern institutions” were effectively abolished. Families were separated as husbands were taken from wives and children were taken from parents. Children were trained to spy on their parents, and would be interrogated about what their parents’ discussions and activities. The entire country was essentially turned into a slave labor camp – people were forced to plant/harvest crops and build dams/levees, all while subsisting only on meager bowls of thin rice gruel. Starving individuals who tried to catch fish, mice, lizards, and other creatures, or looked for wild plants to eat, were severely punished or even killed.
The Khmer Rouge persecuted ethnic minority groups, causing a genocide. Members of the Cham ethnic minority (Muslims) were forced to eat pork and had their mosques used as pig sties. It is estimated that ⅓ of the Cham ethnic minority died during Khmer Rouge rule 150,000 / 400,000 of the ethnic Vietnamese who had lived in Cambodia for generations were expelled. Anti-Vietnam sentiments had deep historical roots among most Cambodians due to the history of invasions and aggression. 200,000 out of 400,000 ethnic Chinese of Cambodia lost their lives during this time as they were considered enemies of the people due to controlling much of Cambodia’s retail trade. Indigenous minority groups were also persecuted and killed during this period. 1.5 to 1.7 million people died during the Khmer Rouge’s reign from torture, executions, starvation, overwork, and exposure to the elements.
Mid-level Khmer Rouge military commanders who opposed Pol Pot returned in December 1978 alongside Vietnamese troops to topple the Khmer Rouge government. To Cambodians, the presence of Vietnamese troops was a painful reminder of an earlier development centuries ago, when the Khmer kingdom had lost a vast expanse of territory in the Mekong Delta to Vietnam. Former Khmer Rouge returnees set up a new government, supported by Vietnam, called the People’s Republic of Kampuchea. A second civil war broke out, spanning twelve years involving three groups that opposed the People’s Republic of Kampuchea: the Khmer Rouge, a non-communist group that followed Sihanouk, and another non-communist group that followed a former prime minister. The U.S. considered the Vietnamese occupation of Cambodia an act of aggression, so they sent money and aid to the groups fighting against the Republic, some of which (ironically) reached the Khmer Rouge communists. Vietnam withdrew its troops from Cambodia in 1989 because it no longer had the resources to continue this occupation, and also due to pressure from the United States and its allies. After Vietnamese troops were officially withdrawn, the Phnom Penh government changed the name of the country to State of Cambodia.
The United Nations Transitional Authority in Cambodia was created in 1991. It oversaw the repatriation of more than 360,000 refugee-seekers from the Thai-Cambodian border. UN-supervised elections were held in 1993, resulting in Prince Sihanouk being re-crowned king, and the country changed its name back to Kingdom of Cambodia. Khmer Rouge hostilities continued until the late 1990s, when several key leaders surrendered to the Phnom Penh government. In 2004, King Sihanouk abdicated again, placing one of his sons on the throne so he could be active in politics. Today, Hun Sen (former Khmer Rouge official who opposed Pol Pot) is the prime minister of Cambodia and is a part of the Cambodian People’s Party.