An investigation of land rentals by Vietnamese farmers in Cambodian border districts reveals the contingent nature of state sovereignty in a postconflict borderland. Cross-border leasing activity has prompted criticism that Cambodia's "national sovereignty" has been weakened. Although it is in the interests of the ruling party to demonstrate firm control of the Cambodia-Vietnam border, land rentals expose three key factors that mitigate this interest. First, they uncover the emergence of competing territorial and political claims in the country's upland borders. Second, the process of state-making at these margins is derailed by dissonant practices among state actors, through their everyday negotiations and actions to accumulate land and capital. Third, the rapid growth of land and commodity markets has intensified local contests for land. These factors render the border porous and weaken the ruling party's exercise of territorial authority. Thus, cross-border rentals expose a fragile and networked form of state sovereignty that is contingent on the ongoing enrollment of disparate state and nonstate actors. This presents risks for a state that is often cast as authoritarian.