The land of demarcation was a line approved by the Pope Alexander VI at the treaty of Tordesillas, in which Portugal und Spain "split" the world into two parts: everything west of the line that was either discovered or about to be discovered would be under Spanish contror; east - Portuguese control. (c).
(the line was moved a bit to the west in 1494, which resulted in brazil belonging to Portugal- but this was before the official discovery of Brazil: this suggests the Portuguese had knowledge of Brazil earlier than claimed! (1500)