This paper seeks to validate the hypothesis that in Brazil, between 1941 and 1948, when the first geographical expeditions to the sertão (backcountry) of Brazil took place, there was a transition in the epistemological style practiced by geographers between the historicist and ecological approach and a positivistic planning approach. Added to both is the need to restructure the colonial legacy of the country's territory, a perspective marked by social geography with a Marxist bias. This transition process is, simultaneously, the construction of another hybrid geographical style and an epistemological point of view of its own. This form of epistemology reflects the configuration of space, i.e., the continuity of the economic and political life of the coast without major modifications. However, the projected planning perspectives for the future occupation of the sertão, seen by the actors of the time as an empty territory, with resources and in which its occupation could gradually reverse Brazil's colonial legacy. Brazilian scientific space is observed as a circulation of knowledge, which is subject to tensions. Conceptual developments occurred in discussions in National Council of Geography (CNG) and Brazilian Institute of Geography and Statistics (IBGE) institutional settings and were called ‘geographical talks/gatherings’, which were published in the Boletim Geográfico and the Revista Brasileira de Geografia. Based on these discussions and controversies, it was possible to differentiate the styles of geography mobilised by actors, as well as to create a general interpretation based on the material analysed. Development geography and a geographical reason are understood as the result of this construction, based on two main factors: the influences of foreign geographies and the nature of the country. The methodology adopted was a geo‐history of knowledge, associated with aspects of Bruno Latour's actor‐network theory. Finally, the paper seeks to contribute to the validation of the epistemological and heuristic virtues typical of the southern hemisphere.