Unlike his magnum opus, the Almagest, translated from Arabic to Latin in the twelfth century, Ptolemy's (ca. 100-ca. 175 CE) Geography remained largely unknown in the Christian West until the late fourteenth century. Its discovery was facilitated by the Byzantine humanist Manuel Chrysoloras (1350-1415), who, arriving in Florence in 1397 to teach Greek, brought with him a Greek manuscript of the famous Ptolemaic text. The translation, begun by Chrysoloras himself in the two years that followed, was completed by his disciple Giacomo da Scarperia (Jacobus Angelus, ca. 1360-1410 or 1411) between 1406 and 1409. Humanists took an immediate interest in the text, both because of the richness of ancient toponymy and for the mathematical description of inhabited lands that distinguished this work from other geographic compilations. Ptolemy explained how to represent the spherical Earth on a flat surface and, for every location, he supplied the geographical coordinates (latitude and longitude) enabling anyone to draw a reliable map of any region. In Florence, the leading cartographers who converted Ptolemy's geographic data into graphic form were Nicolaus Germanus (2nd half of 15th cent.), Piero del Massaio (2nd half of 15th cent.), and Henricus Martellus Germanus (2nd half of 15th cent.). Martellus not only prepared the representation of the two cartographic methods of the entire oikumene (inhabited world) and 27 regional tables that concluded the work; he also added new regional maps to update the geographic information provided by the cosmographer from Alexandria.