International boundaries in the lowland Amazon forest were historically drawn according to the scramble for natural resources. This paper uses a case study from the Peruvian and Brazilian border and the Ucayali and Juruá watersheds to understand the political ecology of a border process from contact to 2004. Results demonstrate how global resource demand and ecological gradients drove boundary formation and the relocation of indigenous labor to the borderlands. Forgotten in the forest after the fall of rubber prices, the borderland Asháninka emerged to challenge loggers incited by the global demand for high grade timber. The transboundary impacts of this resource boom highlight discrepancies between the Brazilian and Peruvian Asháninka's ability to mobilize power. A transboundary political ecology framework is necessary to grasp the heterogeneity and dynamism of natural resource management along boundaries and borderlands forged and tempered by historical resource booms. © 2011 JCG Press.