De Facto Boundaries: Frontier, Environment, and the Materiality of Territory

Abstract This article argues that modern territoriality depended not only on juridico-cartographic abstraction, but also on an explicitly material understanding of territory as physical environment. While scholarship in International Relations and political geography has shown how territory became legible as a bounded political space through delimitation, representation, and legal codification, this article asks how physical environments became politically consequential to territorial rule. It answers this question through a conceptual history of frontier across Anglophone and Sinophone debates. It first recovers early twentieth-century Anglophone understandings of frontier as an environmental limit to state power, focusing on how thinkers such as Friedrich Ratzel, Ellen Churchill Semple, and George Curzon linked political boundary to climate, topography, and human movement. It then shows how Republican-era Chinese scientists and policymakers reworked bianjiang into a modern category for internal frontier marked by environmental constraint, demographic sparsity, and ethnocultural heterogeneity. Across both corpora, environmental limit emerges as a de facto political boundary operating alongside the de jure international border. Frontier thinking, the article argues, persisted not as a premodern residue, but as a way of conceptualising the gap between formal territorial claim and effective territorial governance. Territory thus appears not simply as bounded political space, but as a socio-environmental formation shaped by legal enclosure, environmental knowledge, and the practical limits of governability.