Located at the intersection of the Andes and the Amazon, the piedmont region of Apolo, Bolivia is an interactive frontier that has long been transformed by the movement of persons, resources, and cultural practices between the altiplano and tropical lowlands. Historical documents place the Lecos in Apolo at the time of Inca expansion, and most likely earlier, although the Lecos are largely absent in contemporary ethnographic surveys. Portrayed in the academic literature as on the verge of extinction, Lecos ethnic identity was targeted for revival by the formation of the indigenous organization CIPLA (Indigenous Center of the Lecos People of Apolo) in 1997. The movement to recuperate Lecos identity is explicitly connected to concerns about the land and access to resources through the demand for a Lecos Communal Lands of Origin (TCO) An important premise of my research is that neither the lands being claimed, nor the social actors involved, represent bounded, static entities; instead, the regional landscape of Apolo, and the identity of its original inhabitants have been actively shaped through historical interactions. New ways of understanding cultural variation and change are necessary to replace the essentialist, environmentally deterministic assumptions about indigenous peoples inherited from Steward's cultural ecology, and which continue to guide much environmentally focused research in South America. Rather than portraying indigenous peoples as passively adapted to local environmental conditions, the research program of historical ecology posits that the relationship between peoples and places is mutually interactive and reflective of changes over time. Yet while environments are problematized through an awareness of the constructed nature of landscapes, human societies are too often presented as essentialized givens. In my dissertation, I explore the significance of identity, as a problematic issue, within the research program of historical ecology and focus on the relationship between ethnogenesis and landscape transformation in the interstitial region of Apolo My research was multi-temporal and multi-scalar. Exploring the documentary record from prehistory to present, I reconstruct the ethnohistory of the Lecos of Apolo and trace processes of landscape change. I also conducted fifteen months of ethnographic research in La Paz, Apolo, and three Lecos of Apolo communities, Inca, Irimo, and Santo Domingo. Multi-sited fieldwork among revealed how processes of landscape transformation and ethnogenesis were neither uniform over the region nor consistent across the group. I conclude by arguing that the research program of historical ecology can be useful to contemporary indigenous movements by challenging essentialist assumptions about the relationship between indigenous peoples and places, and replacing these with situated histories of interaction