Water management and iron production were two socio-technical practices deeply entrained with the politics of emerging social distinctions in northern Karnataka during the South Indian Iron Age (1200–300 BCE). In this article, we approach resources by building a theoretical convergence between “resource materialities” and “techno-politics,” which allows us to assess the historically specific constitution of certain materials as culturally valued resources while maintaining analytical attention on how assemblages of technical practices and active material properties shape social conditions. By differentially anticipating and responding to the social and material distributions of a range of dynamic matter (for example, granitic rock, iron ores, bloom, and metal, water, soils, and vegetation), Iron Age peoples transformed substances into resources and simultaneously produced a historically unique political sociology of resource relations. Our approach dissolves the processual distinction between natural resource and cultural product and directs attention to how substances become resources through ongoing historical articulations of humans and nonhumans in contexts oriented by cultural values. Contrasting the material properties and distributions of iron and water resource assemblages allows us to more fully understand the distinctiveness of different forms of techno-politics and resource relations within the same cultural and historical context.