In the Argentinean and Chilean historical experiences, the Araucania, the Pampas and the Patagonia were usually described by criollos authorities as desert regions, placed out of civilization, once during the XIXth century, those places constituted spaces of sovereignty exercise from different indigenous groups. The thesis purpose is to analyze the political speeches made by intellectuals criollos in this context, in order to legitimize expansionist movements, and modernizing projects that intended to incorporate those regions to the public power orbit, civilizing their habitants or extinguishing them if necessary. Although, it attempts to identify the natives answers faced to the new imposing contact modality, accentuating their roles as capable subjects to adapt and resist to the criollos politics. With a comparative approach, this thesis transcends the purpose to identity similar and different traces between the frontier spaces, and the ways of interaction established between criollos and indigenous groups, but also is considered highlight the interconnection points between the experiences in the territorial expansion occurred in Chile and Argentina.