Although South‐East Asia's trading networks have existed for millennia, recent decades have seen markets dramatically intensify in the region's frontiers, bringing social and environmental upheaval. Within political ecology, such transitions are framed as frontier incorporation into global capitalism – a process that has been ongoing since European colonisation. This paper, however, responds to recent calls for commodity network studies to better account for specific material and social variances in “actually existing capitalism.” My analysis focuses on Mondulkiri province in north‐eastern Cambodia, where a boom in cassava cultivation has produced two distinct commodity networks. The first network supplies dried cassava chips to trans‐border markets that serve bioethanol and livestock production. The second network supplies fresh cassava to Vietnamese starch and processed food factories. In order to understand why two market networks have evolved from one crop, I analyse the social, material and spatial relationships in each network. Comparative analysis shows that both networks involve land and labour commodification and respond to global demand. Yet subtle geographical variations in transport networks, migration patterns and the availability of uncleared land, support dried cassava production in some areas and fresh cassava in others. The cassava case shows that although frontier markets are propelled by globally connected processes of commodification, they ultimately take form through co‐productive networks that mould to and shape frontier landscapes. Furthermore, market networks are not only mobilised, but also can be demobilised by environmental, economic and social pressures – a point that frontier incorporation perspectives may overlook. The paper therefore argues for an understanding of frontier geographies as dynamic and constitutive in market formation.