The island of Majorca, the largest of the Balearic islands in the western Mediterranean, had a long history of seafaring. Muslim and Jewish merchants participated in extensive trade across the Mediterranean Sea with Italy, Egypt and Tunisia, and in the 14th century their commerce entered into the Atlantic, reaching as far as England and the Low Countries. Ruled as an independent Muslim kingdom through much of the Early Middle Ages, Majorca only came under Christian rule in 1231, albeit retaining its independence as the Kingdom of Majorca until 1344, when it was permanently annexed to the Crown of Aragon. This coincided with a period of Aragonese expansionism across the Mediterranean to Sardinia and Corsica, Sicily and Greece (Athens and Neopatria), in which Majorcan nautical, cartographic and mercantile expertise was often called upon. Majorcan merchants and seafarers spearheaded the attempt by the Aragonese crown to seize the newly discovered Canary Islands in the Atlantic from the 1340s to the 1360s.
Majorcan cosmographers and cartographers experimented and developed their own cartographic techniques. According to some scholars (e.g. Nordenskiold), the Majorcans were responsible for the invention (c. 1300) of the "normal portolan chart". The portolan was a realistic, detailed nautical chart, gridded by a rhumbline network with compass lines that could be used to deduce exact sailing directions between any two points.
Portolan charts, which appeared rather suddenly after 1300, constitute a sharp departure from all earlier maps. Unlike the circular mappa mundi of Christian academic tradition, the portolan was oriented towards the north, and focused on a realistic depiction of geographic distances with a degree of accuracy that is astounding, even by modern standards. Historians speculate that the portolan was constructed from the first-hand information of mariners and merchants, possibly assisted by astronomers, and were geared for navigational use, in particular the plotting by compass of navigational routes.
Both Majorca and Genoa have laid claim for the invention of the portolan chart, and it is unlikely this will ever be resolved. Few charts have survived to the modern day. The Carta Pisana portolan chart, made at the end of the 13th century (1275–1300), is the oldest surviving nautical chart. The earliest extant ones, from the first half of the 14th century, seem to have been constructed by Genoese cartographers, with Majorcan charts making their appearance only in the latter half of the century. As a result, many historians have argued that the Majorcan cartography derived from the Genoese, citing the mysterious figure of Angelino Dulcert, possibly a Genoese immigrant working in Majorca in the 1330s, as the key intermediary in the transmission. On the other hand, some scholars have embraced the hypothesis first forwarded by A.E. Nordenskiöld, that the surviving charts are misleading, that the earliest Genoese maps were just faithful copies of a conjectured prototype (now lost), composed around 1300 by an unknown Majorcan cosmographer, possibly with the involvement of Ramon Llull. An intermediary position acknowledges Genoese priority, but insists the Majorcan school had an autonomous origin, at best "inspired" (but not derived) from the Genoese. Recent research tends to lean towards the first interpretation, but at the same time curbing some of the more extreme Italian claims and recognizing distinctively Majorcan development.