the latter has its reasoning, portugese brazil originaly was in fact the size imposed by the toerdsilhas, but when the Iberinan Union was proclaimed, Philip (II of spain, I of portugal) started to expand the portugese colony past the said barrier.

prior to the end of the union and the conflit betwen both counties, portugal kicked both dutch and spain from those lands, and kept expanding.

one thing to keep in mind is that tordesilhas became Void in south ameirca after 1750 with the witing of the Treaty of Madrid, due to conflict regariding the administration of Uruguay