In this paper, I analyze the effect of social contextuality in border areas on the formation of identity. Historically, most countries' borders were drawn via military conquests rather than the consent of ethnic groups. Thus, in border areas, there exist different cross-border ethnic groups. This creates a context conducive to formation of a variety of identity: the inhabitants in border areas choose one identity instead of another, depending upon their perceived ethnicity, cultural ties, economic benefits, and political rights. This paper uses the case of the China-Vietnam border area to account for how the social and cultural contexts in border areas affect individuals' choice on their own identity. This paper shows that there is a continuing conflict between "ethnocultural identity" and "national identity" in the China-Vietnam border area.