The main agreement of the treaty was the fixing of the boundary between the Spanish and Portuguese zones of 270 leagues further west of that fixed by inter catera Bulle of 1493. The Western shift of the demarcation line allowed the Spanish to exercise their dominance over more of what they thought was Asia. For the Portuguese, the location of the 370 league line west of the Cape Verde Islands made it possible to control the route to India around the Cape of Good Hope. Although there is no formal evidence, there are a number of indications that the Portuguese were already aware of the existence of land in the South Atlantic in 1493. The new agreement allowed them to guarantee sovereignty over what was to become Brazil, which was officially discovered in 1500. Tordesillas` contract only set the line of demarcation in the leagues of the Cape Verde Islands. He did not indicate the line in degrees, nor did he identify the specific island or the specific length of his league. Instead, the treaty provided that these issues were to be settled by a joint journey that never took place. The number of degrees can be determined by a ratio between the marine ligaments and the degrees that are applied to the Earth, regardless of their supposed size, or by a certain marine league applied to the true size of the Earth and which historian Henry Harrisse calls “our sphere.”  The Treaty of Tordesillas of June 7, 1494 provides for agreements between King Ferdinand II of Aragon and Queen Isabella I of Castile and King John II of Portugal, which establish a new line of demarcation between the two crowns, which goes from pole to pole, 370 leagues west of the Cape Verde Islands. The treaty was eventually signed after complex diplomatic negotiations between ambassadors and lawyers of the two kingdoms. The modification of a dividing line that divides the world between Spain and Portugal led to the birth of Brazil, its eastern end falling into the Portuguese zone. This document is indispensable if we are to understand American history and the economic and cultural relations between Europe and America.
That is why the treaty has become an important reference not only to the history of the Atlantic Ocean, but also to the memory of the world that has allowed the meeting of continents and civilizations separated by unknown oceans. Despite a considerable lack of knowledge of the geography of the so-called New World, Portugal and Spain largely respected the treaty. However, the other European powers did not sign the treaty and generally ignored it, especially those that became Protestant after the Reformation. Similarly, indigenous nations have not recognized the treaty and, as the legal basis for discovery Doctrine, it has been a source of persistent tensions over land ownership until modern times, cited only in 2005 in the U.S. Supreme Court`s Case of Sherrill v. Oneida Nation. [4.] Point, in so far as the above-mentioned ships of the above-mentioned King and the Queen of Castile, León, Aragon, etc., which sail from their kingdoms and seigniories to their property in question on the other side of the aforementioned line, must cross the seas on that side of the line which concern the said King of Portugal, it is therefore agreed and agreed: that the aforementioned ships of this King and Queen of Castile, León, Aragon, etc., cross freely, safely and securely the aforementioned seas of the King of Portugal and within the said line, at any time and without hindrance in both directions. . .