Al-Idrisi (CA. AD 1100–1165)

al-Idrisi was arguably the greatest medieval geographer. A descendant of the prophet Muhammad, this Arab scholar was titled al-Sharif al-Idrisi but known in the West as Geographus Nubiensis, the Nubian geographer. Born in Morocco and educated in Cordoba, he worked in Sicily at the Palermo court of the Norman king Roger II, after whom his book of world geography was called Kitab Rujjar (Book of Roger) in 1154; its full Arabic title is Nuzhat al-mushtaq fi ‘khtiraq al-afaq (Entertainment for One Desiring to Travel Far). A later, shorter world geography, sometimes called “the Little Idrisi,” is known by various Arabic titles. Both are extensively illustrated with maps; the maps in Nuzhat al-mushtaq are full or half-page in size and oriented to the south, while the maps in the later book are smaller and often oriented to the east.

al-Idrisi presided over a collective project, and his Geography is a synthesis of information and cartographic traditions from both Islamic and European cultures. He had traveled in Asia Minor, Europe, and North Africa, and in Sicily, [Page 67]he was able to consult both European and Islamic sources. Because the data were procured from earlier books and travel reports (only 10 authors are named), they are sometimes out-of-date, but the book and accompanying maps are unsurpassed in medieval geography.

The text is a detailed description of the map, supposedly based on the Arabic version of Marinus's map, created under Caliph al-Ma'mun (AD 813–833) and engraved on a silver disk. The silver prototype was lost, but the text is accompanied by a round, schematic map of the world and 70 rectangular maps of the 70 parts into which al-Idrisi had divided the world. The projection used remains unexplained, although al-Idrisi followed the Ptolemaic foundation, adopted by the early Islamic scholars, whereby the round Earth is divided into quarters and only the Inhabited Quarter is described. It is astronomically divided into seven latitudinal belts, “climates,” leaving off the extreme north and the equatorial south. Although familiar with coordinates, al-Idrisi did not use them. His innovation was in using, instead of meridians, 10 longitudinal divisions of the parallel latitudinal climates. The climates are numbered from south to north, as in the scheme developed by Eratosthenes, and the numbers of sections go west to east. After a brief general introduction, the text follows the map's division into 70 sections. al-Idrisi names the most place names since Ptolemy, expands and updates the medieval Arabic geographical inventory, and describes for the first time many identifiable locations, which he connects by itineraries.

Earth is shown surrounded by Encircling Sea al-Bahr al-Muhit (the Greek Ocean). The western limit is the prime meridian drawn through the westernmost part of Africa (the Fortunate Isles in the Atlantic are also included). The easternmost country is Sila (Korea), supposedly at 180°. The southern portion of the round world map is filled with the African landmass, not shown on sectional maps. Africa is extended eastward to form the southern coast of the Indian Ocean, which remains open in the Far East. The northern limit is 64°, practically coinciding with the Polar Circle. The maps are color coded and distinctive and, together with the special features of the text, make it possible to speak of the “Idrisi school,” which influenced both Arabic and European cosmographers. The book Nuzhat al-mushtāq became the first secular Arabic work printed in Europe (in Rome in 1592); a Latin translation was published in 1619 in Paris. These editions did not include the maps, but a pieced-together Latin version of the sectional map of the world was produced in Paris by Petrus Bertius in the 1620s. In honor of the Arab scholar, the name IDRISI has been given to a grid-based geographic analysis system and related GIS (geographic information system) and remote sensing software and to an Arabic electronic search engine with bilingual (Arabic/English) indexing and publishing capabilities.

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