Despite engagement and collaboration between the two countries, Vietnamese individuals have been the targets of xenophobic attacks by opposition political parties critical of Hun Sen's policies since the 1990s.

[5][6] Although xenophobic sentiments have been a continuing source of concern, they have not been a barrier towards neighborly ties within the context of Southeast Asia and other international affairs.

[7][8][4][9] Relations between Cambodia and Vietnam date back to when Chey Chettha II, in order to balance the influence of the Siamese forces, which had devastated the previous capital at Longvek during the reign of his father, had struck an alliance with Vietnam and married Princess Nguyễn Phúc Ngọc Vạn, a daughter of Lord Nguyễn Phúc Nguyên, in 1618.

[10][11] In return, the king had granted the Vietnamese the right to establish settlements in Mô Xoài (now Bà Rịa), in the region of Prey Nokor—which they colloquially referred to as Sài Gòn, and which later became Ho Chi Minh City.

[15] Favors were granted to allow more Vietnamese settlers and by the reign of Emperor Minh Mạng, Vietnam chose to impose its rule directly, relegating the Cambodian court to a minor role.

[19] When the Japanese invaded Indochina in 1940, Vietnamese nationalists in Cambodia launched a brief but unsuccessful attempt to attack the French colonial administrators.

[20] With independence in 1954, Cambodia legislated a citizenship law based on knowledge in the Khmer language and national origin; this effectively excluded most Vietnamese and Chinese Cambodians.

During a Sangkum congress in 1962, politicians debated on the issue of citizenship on Cambodia's ethnic minorities and a resolution was passed not to grant naturalization of Vietnamese residents.

[22] When Lon Nol assumed power in 1970, the Khmer Republic government launched a propaganda campaign to portray the ethnic Vietnamese as agents of the Vietcong.

[29] In November 1992, the Khmer Rouge which controlled northwestern parts of Cambodia, passed a resolution to target systematic killings of Vietnamese soldiers and civilians.

The Khmer Rouge formally surrendered to the government in 1999 but ethnic Vietnamese continue to face discrimination in Cambodia, both as physical intimidation from the general population and administrative threats by local authorities.

Anti-Vietnamese are familiar rallying cries from politicians in campaigns during the general elections and become even more acute when disputes flared in the news between the two countries.

[34] Smaller populations may be found in Phnom Penh as well as southeastern provinces bordering Vietnam, namely Prey Veng, Svay Rieng,[35] Kampong Cham, Kampot, Kandal, Kratié,[36] and Takéo.

[42] Vietnamese adherents of Roman Catholicism consist of descendants of refugees that fled the religious persecution during the reign of Tự Đức.

[48] Field research carried out by ethnologists such as Stefan Ehrentraut shows that only a minority of Vietnamese children attend public schools, with figures varying across different provinces.

In Kampong Chhnang and Siem Reap where the Vietnamese live along the river banks, enrollment into public schools fare below 10%, whereas in other provinces such as Kampot and Kratie the proportion are higher.

When Cambodia gained independence in 1953, the Sihanouk-led government phased out most of the Vietnamese civil servants with Cambodians, and they sought employment in banks and commercial enterprises as secretaries and other office-based positions.

In the 1960s, urban-dwelling Vietnamese with lower education backgrounds also worked as mechanics in car repair and machine shops owned by Chinese businessmen.

Vietnamese immigrants that settled in the countryside worked as fishermen along the Tonle Sap lake and Mekong river,[43] and also as rubber plantation workers in Kampong Cham and Kratie provinces.

One example is Sok Kong, the head of the business conglomerate Sokimex which owns state concessionaires in the country's petroleum, tourism and entrepot industries.

[59] A minority of Vietnamese residents were able to obtain citizenship only after paying bribes to interior ministry officials, or were married to Khmer spouses.

[60] As a result, the Vietnamese faced legal restrictions from getting access to public healthcare, education, employment and buying land for housing as the majority do not carry Cambodian citizenship.

[68] During this same period of time, the Khmer Rouge which has earlier refused to participate in the elections also espoused similar anti-Vietnamese sentiments with mainstream political parties albeit on a more extreme form.

The Khmer Rouge would issue statements and radio broadcasts accusing UNTAC of collaborating with Vietnam, and called for expulsion of the Vietnamese population through force.

[74][75] When the CNRP narrowly lost the 2013 elections, they launched a series of anti-government protests between 2013-2014 which resulted in incidents of Vietnamese shops in Phnom Penh being ransacked.