The article reconstructs spatial thinking about Belarus as a national territory in the early twentieth century. Different approaches to national mental mapping, suggesting and revising boundaries with analogous national territories of other national groups (first of all, Poles and Lithuanians), were developed within the rising nationalist movement. The author reconstructs the most influential discursive practices of Belarusian nationalism by looking into political documents as well as the few national Belarusian periodicals existing at the time, belles lettres, and educational materials. Targeting the broad Belarusian public (first of all, peasantry), these literatures collectively pursued the goal of their nationalization. Intertextual analysis allows the author to discuss the rival projects of the territorialization of Belarus (including the supranational idea of restoring the ancient Grand Duchy of Lithuania as a commonwealth of Belarusians, Lithuanians, and other nationalities); various criteria of identifying belonging to a nation, with language becoming the primary factor; and the political implications of different versions of the Belarusianization of territory.