The historical processes of the Ava-Guarani peoples in the region between Foz do Iguaçu (Brazil) and Ciudad del Este (Paraguay), led to a discussion on the border, mobility and territoriality. In this sense, this essay aims to carry out a brief conceptual rescue on topics that are widely discussed by the academy, but which in the historical construction process of the Itaipu Hydroelectric Plant (1982-1988) seems to have been forgotten. With this, it is necessary to think more broadly, about the interferences in the territory and the dynamics taken by these original peoples. When talking about the frontier, try to bring the Guarani’s conception of this demarcation controlled by the National State. Despite being considered important physical structures that impose rules and segregation for non-Indians it portrays only a symbolic space without a flag.