Victims
The Khmer Rouge regime frequently arrested and often executed anyone suspected of connections with the former Cambodian government or foreign governments, as well as professionals, intellectuals, the Buddhist monkhood, and ethnic minorities. Even those who were stereotypically thought of as having intellectual qualities, such as wearing glasses or speaking multiple languages, were executed for fear that they would rebel against the Khmer Rouge. As a result, Pol Pot has been described by journalists and historians as "a genocidal tyrant" and the Cambodian genocide as “the purest genocide of the Cold War era". The attempt to purify Cambodian society along racial, social and political lines led to purges of Cambodia's previous military and political leadership, along with business leaders, journalists, students, doctors, and lawyers. Ethnic Vietnamese, ethnic Thai, ethnic Chinese, ethnic Cham, Cambodian Christians, and other minorities were also targeted. The Khmer Rouge forcibly relocated minority groups and banned their languages. The government exploited thousands of desensitized, conscripted children in their early teens to commit mass murder and other atrocities during and after the genocide. The indoctrinated children were taught to follow any order without hesitation. During this period, the children were deployed mainly in unpaid support roles, such as ammunition-carriers, and also as combatants.
Vietnamese
The Khmer Rouge initially ordered the expulsion of ethnic Vietnamese from Cambodia but then massacred large numbers of that population as they attempted to flee the country.The regime then prevented the remaining 20,000 ethnic Vietnamese from fleeing, and much of this group was also executed.The Khmer Rouge also used the media to support their goals of genocide. Radio Phnom Penh called on Cambodians to "exterminate the 50 million Vietnamese." Additionally, the Khmer Rouge conducted many cross-border raids into Vietnam where they slaughtered an estimated 30,000 Vietnamese civilians.
Chinese
The state of the Chinese Cambodians during the Khmer Rouge regime was alleged to be "the worst disaster ever to befall any ethnic Chinese community in Southeast Asia." Cambodians of Chinese descent were massacred by the Khmer Rouge under the justification that they "used to exploit the Cambodian people". The Chinese were stereotyped as traders and moneylenders associated with capitalism, while historically the group had attracted resentment due to their lighter skin color and cultural differences. At the beginning of the Khmer Rouge regime in 1975, there were 425,000 ethnic Chinese in Cambodia; by the end of 1979 there were just 200,000 stuck at Thai refugee camps or Cambodia. 170,000 Chinese fled Cambodia to Vietnam while others were repatriated.
Cham Muslims
The fiercest extermination campaign was directed against the ethnic Chams Muslim minority. Islam was seen as an alien and foreign culture that did not belong in the new Communist system. Pol Pot began using intimidation efforts against the Chams that included the assassination of village elders but ultimately ordered the full-scale mass killing of Cham people.
The patterns were consistent throughout the killings of the Cham people were, first, the dismantling of the communal structure through the murder of the leaders of the Cham Muslim communities, which include the Muftis, Imams, and other learned men of influence; second, the dismantling of the Cham’s Islamic and ethnic identities through the restrictions against distinct practices which distinguished the Cham from the Khmers; third, the dispersal of the Cham from their respective communities, either by forced labour in the fields, or arresting them for alleged plots of resistance or rebellion against the CPK.
During the Khmer Rouge era, all religions, including both Buddhism and Islam were persecuted. According to Cham sources, 132 mosques were destroyed during the Khmer Rouge era, many others were desecrated, and Muslims were not allowed to worship. Muslims were forced to eat pork and were murdered when they refused. Whole Cham villages were exterminated. Chams were not permitted to speak their language. Moreover the Cham children were taken away from their parents and raised as Khmers
Religious groups
Under the leadership of Pol Pot, who was an ardent atheist, the Khmer Rouge had a policy of state atheism. All religions were banned, and the repression of adherents of Islam, Christianity and Buddhism. It is estimated that up to 50,000 Buddhist monks were massacred by the Khmer Rouge.