This study of river names seeks to deepen our understanding of the pre-modern environmental history of northern Vietnam. A performative practice, naming places often reveals the transformation of a physical environment into a cultural one. By analysing the names given to antecedents of the Red River in northern Vietnam, this article argues that each historical name reflected its users’ perception of their relationship with a respective river. Toponyms like Lô, Phú Lương, Nhị, and ‘Great River’, therefore, did not simply represent the present-day Red River — a geographical unit that dates to the French colonial period.