Over the past 600 years, commodity frontiers - processes and sites of the incorporation of resources into the expanding capitalist world economy - have absorbed ever more land, ever more labour and ever more natural assets. In this paper, we claim that studying the global history of capitalism through the lens of commodity frontiers and using commodity regimes as an analytical framework is crucial to understanding the origins and nature of capitalism, and thus the modern world. We argue that commodity frontiers identify capitalism as a process rooted in a profound restructuring of the countryside and nature. They connect processes of extraction and exchange with degradation, adaptation and resistance in rural peripheries. To account for the enormous variety of actors and places involved in this history is a critical challenge in the social sciences, and one to which global history can contribute crucial insights.