Romans but which had not yet been standardized in 1450. If miglia is taken as the Roman mile, this means the circumference would be about 34,468 km. If miglia is taken as the Italian mile, the stated circumference would be about 43,059 km. The actual meridional circumference of the Earth is close to both these values at about 40,008 km or approximately 24,860 English miles. So the stated range taken in Roman miles is 86-92% of modern measurements, whereas taken in Italian miles is 108-115% of the current measurement. Sources The sources for the map were existing maps, charts, and manuscripts, which were combined with written and oral accounts of travelers. The text on the map mentions many of these travel accounts. Some of the main sources were accounts of the journeys of Italian merchant and traveller Niccolò de' Conti. Setting out in 1419, De Conti traveled throughout Asia as far as China and present-day Indonesia during a period of 20 years. In the map, many new location names and several verbatim descriptions were taken directly from de Conti's account. The "trustworthy source" whom Fra Mauro quotes is thought to have been de' Conti himself. The book of travels of Marco Polo is also believed to be one of the most important sources of information, in particular about East Asia. For Africa, Fra Mauro relied on recent accounts of Portuguese exploration along the west coast. The detailed information on the southeastern coast of Africa, was likely brought by an Ethiopian embassy to Rome in the 1430s. Fra Mauro also probably relied on Arab sources. Arab influence is suggested by the north-south inversion of the map, an Arab tradition exemplified by the 12th-century maps of Muhammad al-Idrisi. As Piero Falchetta notes, many geographical facts are reflected in Fra Mauro map for which what Fra Mauro's source was is not clear, as no similar information is found in other preserved Western maps or manuscripts of the period. This situation can be at least partially explained by the fact that, besides the existing maps and manuscripts, important sources of information for his map were oral accounts from travelers — Venetians or foreigners — coming to Venice from all parts of the then-known world. The importance of such accounts is indicated by Fra Mauro himself in a number of inscriptions. An even earlier map, the De Virga world map (1411–1415) also depicts the Old