The Amazon region, since the discovery of the Americas has been the stage of disputes, starting with the one between the Portuguese and Spanish empires. Over the centuries, this huge area has also attracted a combination of myths and realities. The stories of the "El Dorado", the "Country of Canela" and the myth of the "Brazil Island" are the starting points in conceptualizing the Amazon like an enormous area with unknown wealth and of great interantional interest and dispute. The Brazilian Amazon is studied here starting from the period where the first European impact occurred, in the context of the Treaty of Tordesillas, with the Scout movement which expanded the region limits, which was later legalized in 1750 when Portugal and Spain signed the Madrid treaty. In conjunction with this geopolitical strategy, the Portuguese crown struggled for the occupation of this space until the end of the XVIII century. After the initial expansion of the borders, Portuguese diplomacy constantly worked on enforcing the achieved expansion throughout successive periods with several treaties between Brazil and neighboring Latin American countries. One of the objectives if this work was to discuss the issues of the definition of borders and territorial disputes, which began with the treaties of limits in the colonial period, which would be concluded only during the Republican period in Brazil. In addition, it was aimed to analyze the developments in the setting of the border limits in the Amazon region, which were mostly attributed to diplomatic actions. The work developed in doctrine to expand the concept of studies in geopolitics, from the classical geopolitics and their precursors, is also herewith described. The basic concepts of geopolitics discipline were formed by the work developed by great scholars such as, Ratzel, Kjellén, Mackinder, Haushofer Mahan and Spykman. The latter, finalized this phase of the history of Classical Geopolitics with his synthesis. Geopolitics, which was banned in Europe after World War II, finds refuge in South America, having Brazil as its main exponent. This work aimed to examine the thinking of the Brazilian military scholars of geopolitics, linked the doctrine of the War College (ESG), focused on the Amazon. The factors that contributed to the reevaluation of strategy in Brazil, assessing the importance given to the Amazon by the policymakers in the region and its integration into the Brazilian territory during the period when the power was mainly hold by the military. The role of foreign policy in the international context in the 1970s would provide the right setting to the idealization of the Treaty of Cooperation of the Amazon. Finally, the institutional and geostrategic way of the Calha Norte Project (PCN) as a process of territorialization of the political frontier, aiming to understand their strategic and geopolitical implications.