Frontiers of Water and Wind: Environmental Dynamics, Maritime Mobility, and the Making of the Portuguese Empire

This article examines Portuguese imperial expansion across the Atlantic and Indian Oceans through the lens of environmental history, arguing that mobility, ecological variability, and locally grounded environmental knowledge were central to the making, negotiation, and crossing of early modern imperial frontiers. Rather than advancing through stable territorial incorporation, Portuguese expansion developed through interconnected socio-ecological systems established across environmental frontiers and maritime interfaces. These spaces were neither fixed boundaries nor empty margins, but dynamic zones of interaction in which imperial projects were hindered by local communities, established networks of mobility and exchange, and more-than-human processes. Their configuration was shaped by seasonal rhythms, navigational practices, resource availability, and the material infrastructures through which movement, settlement, and resource access were organised. Drawing on travel accounts, administrative correspondence, cartographic materials, and ecological studies, the article situates Portuguese expansion within dynamic landscapes where human interventions intersected with local knowledge, material infrastructures, and changing environmental conditions. A comparative analysis of Madeira, Cabo Verde, the Cape, and Sofala reveals how wind and monsoon regimes, coastal geomorphologies, hydrological conditions, resource availability, and African and Atlantic ecological knowledge conditioned the possibilities and limits of imperial mobility, settlement, provisioning, and infrastructure building. By foregrounding environmental contingency and circulatory regimes, the article reconceptualizes the early modern Portuguese Empire as a differentiated and environmentally contingent formation in which imperial frontiers were continually produced, negotiated, crossed, and reconfigured through socio-ecological interactions. In doing so, it brings environmental history into dialogue with frontier and border studies, showing how maritime mobility and environmental change contributed to the making and transformation of territorial and spatial boundaries in the early modern world.