When French colonial rule came to an end in the middle of the 20th Century, theKhmers of the Mekong Delta had no choice but to negotiate relations with two different states, South Vietnam and Cambodia. In the period of French colonial rule, during which the two regions were integrated as a super-national colonial space, the Khmers lived in a social environment connected by the Khmer language and Theravāda Buddhism, which was formed over a wide area extending from the Mekong Delta to Cambodia. However, this social environment was gradually forced to change under the Ngô Đình Diệm government of South Vietnam, which gained control of the Mekong Delta as the French withdrew. The Diệm regime carried out nationality change, abolished Khmer language education at public schools, restructured existing Khmer and Buddhist organizations, and sought to sever ties between the Khmers of the Mekong Delta and Cambodian society through the national border. Discontent with the Diệm regime grew among local people and in the Theravāda Buddhist community, which regarded the existing relationship with Cambodian society as valuable and meaningful, and before long, some people began participating in anti-government movements. This article focuses on the problems of language, Buddhism, and belonging in a community in the Mekong Delta province of Sóc Trăng and examines the friction that arose between local people and the emerging South Vietnamese state in the process of creating a new nation-state.