how did the first one get enforced?
The Portuguese King sent a threatening letter to the Catholic Monarchs, King Ferdinand and Queen Isabella, stating that by the Treaty of Alcáçovas signed in 1479 and by the 1481 papal bull "Æterni regis" that granted all lands south of the Canary Islands to Portugal, all of the lands discovered by Columbus belonged, in fact, to Portugal.
Treaty of Tordesillas
After learning of the Castilian-sponsored voyage, the Portuguese King sent a threatening letter to the Catholic Monarchs, King Ferdinand and Queen Isabella, stating that by the Treaty of Alcáçovas signed in 1479 and by the 1481 papal bull "Æterni regis" that granted all lands south of the Canary Islands to Portugal, all of the lands discovered by Columbus belonged, in fact, to Portugal. 
what is the habitat of a dodo bird It may have inhabited the woods on the drier coastal areas of south and west Mauritius. what is dodo? It is an extinct flightless bird that was endemic to the island of Mauritius, east of Madagascar in the Indian Ocean. what is this type of bird you just mentioned? These are birds that through evolution have lost the ability to fly. where do they originate? UNANSWERABLE name some of these birds Cretaceous patagopterygiformes, hesperornithids, the Cenozoic phorusrhacids etc. where did the above mentioned island take its name from? In 1598, Dutch squadron under Admiral Wybrand van Warwyck landed at Grand Port and named the island "Mauritius", in honour of Prince Maurice van Nassau, stadtholder of the Dutch Republic. was this island invaded by the foreign settlers? Yes, the Portuguese what did they do? The Treaty of Tordesillas purported to give Portugal the right to colonize this part of world; they established a visiting base; Diogo Fernandes Pereira named the island "Ilha do Cirne" ("Island of Cirne"). when did they sign this treaty? June 7, 1494 was there any other treaty along with this? Yes, the Treaty of Zaragoza
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Treaty of Tordesillas [SEP] Signing and enforcement
The Portuguese were unlikely to go to war over the islands encountered by Columbus, but the explicit mention of India was a major issue. As the Pope had not made changes, the Portuguese king opened direct negotiations with the Catholic Monarchs to move the line to the west and allow him to claim newly discovered lands east of the line. In the bargain, John accepted "Inter caetera" as the starting point of discussion with Ferdinand and Isabella, but had the boundary line moved 270 leagues west, protecting the Portuguese route down the coast of Africa and giving the Portuguese rights to lands that now constitute the Eastern quarter of Brazil.