This article examines boundary disputes between Qajar Persia and the emerging state of Afghanistan in the nineteenth century. It argues that disputes between these two Islamic polities were central to the creation of modern states through the territorialization of political identity, in the form of border delineation. The demarcation of territorial boundaries represented the ‘indigenization’ of Western norms of statehood. Indigenous political actors increasingly understood and envisaged their political communities in terms of territorial states, reinterpreting and redeploying European political concepts in indigenous spaces. The Perso-Afghan case exemplifies the assimilation of ideas of political territoriality, central to the construction of a modern state-based international order, in Muslim regions outside direct colonial control.