The ecologically and culturally rich Amazonian border zones are increasingly targeted for development and the exploitation of natural resources, even as these zones often double as existing or proposed sites for the conservation of biodiversity and protection of indigenous lands. Governmental and Non-Governmental Organizations alike project their goals from central offices onto borderland landscapes assumed to be empty of local people but full of valuable resources, biodiversity or development potential. Simultaneously, loggers, miners, drug traffickers, and others operate illegally or quasi-legally within these border zones and, in the absence of a strong governmental presence, cultivate the borderland's reputation as a violent hinterland. Within this complex borderland reality, the local people (indigenous and non-indigenous), largely invisible to authorities, struggle to survive with subsistence strategies while either negotiating with illegal interlopers to supplement their income or resisting them for their very survival. The resulting landscape is a tangle of overlapping and competing concessions, conservation units, and indigenous territories whose contestation and resulting confusion advances the agenda of illegal extractivists and drug traffickers. This study highlights the continued importance of fieldwork in geography. Here, field-based research provides insight into the poorly understood borderlands of Peru and Brazil. Research used a combination of participatory methods, Geographic Information Systems, ethnography, document research, and remote sensing to analyze mapping, logging, and coca cultivation within four borderland watersheds. These data were combined with regional data on coca eradication, resource concessions, conservation units, and indigenous territories from both Brazil and Peru. Field-based results demonstrate these borderlands to be highly contested and poorly mapped with an exploitative and poorly managed timber industry and a dynamic front of coca cultivation contributing to social disruption and environmental degradation. More fieldwork is needed to generate the geographic information necessary for sustainable development and conservation planning and to help local people defend their territory from illegal operators and the imposition of state resource concessions. Ecological Economic Zoning is recommended as a participatory policy framework to improve geographic information and long term planning. / text