Medieval Islamic geography and cartography were the studies of geography and cartography in the Muslim world during the Islamic Golden Age (variously dated between the 8th century and 16th century). Muslim scholars made advances to the map-making traditions of earlier cultures, explorers and merchants learned in their travels across the Old World (Afro-Eurasia). Islamic geography had three major fields: exploration and navigation, physical geography, and cartography and mathematical geography. Islamic geography reached its apex with Muhammad al-Idrisi in the 12th century.
History
8th and 9th century Islamic geography began in the 8th century, influenced by Hellenistic geography, combined with what explorers and merchants learned in their travels across the Old World (Afro-Eurasia). Muslim scholars engaged in extensive exploration and navigation during the 9th-12th centuries, including journeys across the Muslim world, in addition to regions such as China, Southeast Asia and Southern Africa. Various Islamic scholars contributed to the development of geography and cartography, with the most notable including Al-Khwārizmī, Abū Zayd al-Balkhī (founder of the "Balkhi school"), Al-Masudi, Abu Rayhan Biruni and Muhammad al-Idrisi. Islamic geography was patronized by the Abbasid caliphs of Baghdad. An important influence in the development of cartography was the patronage of the Abbasid caliph al-Ma'mun, who reigned from 813 to 833. He commissioned several geographers to perform an arc measurement, determining the distance on Earth that corresponds to one degree of latitude along a meridian (al-Ma'mun's arc measurement). Thus his patronage resulted in the refinement of the definition of the Arabic mile (mīl in Arabic) in comparison to the stadion used in the Hellenistic world. These efforts also enabled Muslims to calculate the circumference of the Earth. Al-Mamun also commanded the production of a large map of the world, which has not survived, though it is known that its map projection type was based on Marinus of Tyre rather than Ptolemy. Islamic cartographers inherited Ptolemy's Almagest and Geography in the 9th century. These works stimulated an interest in geography (particularly gazetteers) but were not slavishly followed. Instead, Arabian and Persian cartography followed Al-Khwārizmī in adopting a rectangular projection, shifting Ptolemy's Prime Meridian several degrees eastward, and modifying many of Ptolemy's geographical coordinates. Having received Greek writings directly and without Latin intermediation, Arabian and Persian geographers made no use of T-O maps. In the 9th century, the Persian mathematician and geographer, Habash al-Hasib al-Marwazi, employed spherical trigonometry and map projection methods in order to convert polar coordinates to a different coordinate system centred on a specific point on the sphere, in this the Qibla, the direction to Mecca. Abū Rayhān Bīrūnī (973–1048) later developed ideas which are seen as an anticipation of the polar coordinate system. Around 1025, he describes a polar equi-azimuthal equidistant projection of the celestial sphere. However, this type of projection had been used in ancient Egyptian star-maps and was not to be fully developed until the 15 and 16th centuries.
Khordadbeh–Jayhani tradition The works of Ibn Khordadbeh (c. 870) and Jayhani (c. 910s) were at the basis of a new Perso-Arab tradition in Persia and Central Asia. The exact relationship between the books of Khordadbeh and Jayhani is unknown, because the two books had the same title, have often been mixed up, and Jayhani's book has been lost, so that it can only be approximately reconstructed from the works of other authors (mostly from the eastern parts of the Islamic world) who seem to have reused some of its contents. According to Vasily Bartold, Jayhani based his book primarily on the data he had collected himself, but also reused Khordadbeh's work to a considerable extent. Unlike the Balkhi school, geographers of the Khordadbeh–Jayhani tradition sought to describe the whole world as they knew it, including the lands, societies and cultures of non-Muslims. As vizier of the Samanid Empire, Jayhani's diplomatic correspondence allowed him to collect much valuable information from people in faraway lands. Nevertheless, Al-Masudi criticised Jayhani for overemphasising geological features of landscapes, stars and geometry, taxation systems, trade roads and stations allegedly few people used, while ignoring major population centres, provinces and military roads and forces.
Balkhi school The Balkhī school of terrestrial mapping, originated by Abu Zayd al-Balkhi (from Balkh) in early 10th century Baghdad, and significantly developed by Istakhri, had a conservative and religious character: it was only interested in describing mamlakat al-Islām ("Islamic lands"), which the school divided into 20 or more iqlīms ("climes" or provinces). Balkhi and his followers reoriented geographic knowledge in order to bring it in line with certain concepts found in the Quran, emphasised the central importance of Mecca and Arabia, and ignored the non-Islamic world. This distinguished them from earlier geographers such as Ibn Khordadbeh and Al-Masudi, who described the whole world as they knew it. The geographers of this school, such as Istakhri, al-Muqaddasi and Ibn Hawqal, wrote extensively of the peoples, products, and customs of areas in the Muslim world, with little interest in the non-Muslim realms, and produced world atlases, each one featuring a world map and twenty regional maps.
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