Age of Discovery - Background

Background

See also: Early world maps and Exploration of Asia

European medieval knowledge about Asia beyond the reach of Byzantine Empire was sourced in partial reports, often obscured by legends, dating back from the time of the conquests of Alexander the Great and his successors. Another source were Radhanite Jewish trade networks of merchants established as go-betweens between Europe and the Muslim world during the time of the Crusader states.

In 1154 Arab geographer Muhammad al-Idrisi created a description of the world and world map, the Tabula Rogeriana, at the court of King Roger II of Sicily, but still Africa was only partially known to either Christians, Genoese and Venetians, or the Arab seamen, and its southern extent unknown. There were reports of great African kingdoms beyond the Sahara, but the factual knowledge was limited to the Mediterranean coasts and little else since the Arab blockade of North Africa precluded exploration inland. Knowledge about the Atlantic African coast was fragmented and derived mainly from old Greek and Roman maps based on Carthaginian knowledge, including the time of Roman exploration of Mauritania. The Red Sea was barely known and only trade links with the Maritime Republics, the Republic of Venice especially, fostered collection of accurate maritime knowledge.

Indian Ocean trade routes were sailed by Arab traders. Between 1405 and 1421 Chinese third Ming emperor Yongle sponsored a series of long range tributary missions under the command of Zheng He (Cheng Ho). The fleets visited Arabia, East Africa, India, Malay Archipelago and Thailand. But the journeys, reported by Ma Huan, a Muslim voyager and translator, were halted abruptly after the emperor's death and were not followed up, as the Chinese Ming dynasty retreated in the haijin, a policy of isolationism, having limited maritime trade.

By 1400 a Latin translation of Ptolemy's Geographia reached Italy coming from Constantinople. The rediscovery of Roman geographical knowledge was a revelation, both for mapmaking and worldview, although reinforcing the idea that the Indian Ocean was landlocked.