to the British Isles (or even beyond, to the place that the texts call Thule), but it is unclear if they circumnavigated Africa or crossed the Atlantic reaching America (which they would have called Antillia) — something most likely achieved by the Norsemen in the 10th century. In the Indian and Pacific oceans, the oceanic navigations made it possible to populate all the archipelagoes (Polynesian navigation). However, the possibility of reaching South America is still a matter of debate — the settlement of the Americas through the Bering Strait would not have required navigation, or in any case, coastal navigation would have sufficed — as well as other possible pre-Columbian transoceanic contacts. In the first quarter of the 15th century, the Chinese expeditions led by Zheng He reached the African coasts of the Indian Ocean. It has been proposed that they might have reached the South Atlantic and even America and Europe, but this proposal has not been accepted beyond mere speculation.Mediterranean navigation, which the Romans had come to control (undisputed Mare Nostrum since their victories over the Carthaginians in the Punic Wars [264-146 BC], the Egyptians during the Battle of Actium [31 BC], and pirates), was once again a contested environment in the Middle Ages, from the moment the Vandals managed to attack the Italian coasts from the sea. In the 6th century, the Byzantines managed to regain control, and in the 7th century it was the Arabs who ended up dividing the Mediterranean area, which even the Vikings and Normans were able to access. Since the time of the Crusades, Venetian, Genoese and Crown of Aragon navigators also had a strong presence. Knowledge of the compass, transmitted to the Europeans by the Arabs (who in turn had obtained it from the Chinese), together with other improvements in astronomical techniques (astrolabe, Jacob's staff, sextant, cartographic techniques (portulan and shipbuilding (caravel, nau, galleon), made the Age of Discovery — initially led by the Portuguese and Castilians — possible, especially after Henry the Navigator impulsed the school of Sagres. In 1492, the first voyage of Christopher Columbus took place. In 1488, Bartolomeu Dias rounded the Cape of Good Hope, which opened the route to the Indian Ocean — Vasco de Gama reached Calicut (India) in 1498. Between 1519 and 1521, the Magellan-Elcano expedition circumnavigated the world — measuring the geographical longitude with the method of its scientific organizer, Rui Faleiro. Until