AT and O map orO–T orT–O map (orbis terrarum, orb or circle of the lands; with the letter T inside an O), also known as anIsidoran map, is a type ofearly world map that represents theAfro-Eurasian landmass as a circle (= O) divided into three parts by a T-shaped combination of the Mediterranean sea, the river Tanais (Don) and theNile.^[1] The origins of this diagram are contested, with some scholars hypothesizing an origin in Roman or late antiquity, while others consider it to have originated in 7th or early-8th century Spain.^[2]

The earliest surviving example of a T-O map is found in a late-7th or early-8th century copy ofIsidore of Seville's (c. 560–636)De natura rerum, which alongside hisEtymologiae (c. 625) are two of the most common texts to be accompanied by such a diagram in the Middle Ages.^[3] A later manuscript added the names ofNoah's sons (Sem,Iafeth andCham) for each of the three continents (seeBiblical terminology for race).^[4] A later variation with more detail is theBeatus map drawn byBeatus of Liébana, an 8th-century Spanishmonk, in the prologue to hisCommentary on the Apocalypse.

The earliest T-O maps are closely associated with two sections of the work of Isidore of Seville:

De Natura Rerum 48.2-3 (drawn verbatim fromHyginus'De astronomia 1.9(8) andAugustine of Hippo'sCity of God 16.17^[5]):

So the earth may be divided into three sides (trifarie), of which one part isEurope, anotherAsia, and the third is calledAfrica. Europe is divided from Africa by a sea from the end of theocean and thePillars of Hercules. And Asia is divided fromLibya withEgypt by theNile... Moreover, Asia – as the most blessedAugustine said – runs from the southeast to the north ... Thus we see the earth is divided into two to comprise, on the one hand, Europe and Africa, and on the other only Asia.^[6]

Etymologiae 14.2.1:

The world is called round after the roundness of a circle, because it is like a wheel [...] Because of this, theOcean flowing around it is contained in a circular limit, and it is divided in three parts, one part being called Asia, the second Europe, and the third Africa.^[7]

Although Isidore taught in theEtymologiae that the Earth was "round", his meaning was ambiguous and some writers think he referred to a disc-shaped Earth. However, other writings by Isidore make it clear that he considered the Earth to bespherical.^[8][9] Indeed, the spherical Earth had been the prevailing scholarly assumption since at leastAristotle, who had delineated afrigid clime at thepoles, atorrid clime near theequator, and a habitabletemperate clime in between.

The T and O map represents only half of the spherical Earth,^[10] presumably a convenientprojection of the known northern temperate region. It was believed that no one could cross the torrid equatorial clime and reach the unknown lands to the south, theantipodes.^[10][11]

TheT is theMediterranean, theNile, and theDon (formerly called the Tanais) dividing the threecontinents,Asia,Europe andAfrica, and theO is the encirclingocean.^[12] In line with Isidore's description, Asia is normally depicted as equal in size to Africa and Europe combined.^[13] The majority T-O maps are oriented to the east, though examples of north, south and westward orientation can also be found.^[14]

The idea thatJerusalem was generally represented in the center of the map as the navel of the world, theumbilicus mundi, is a false generalisation from a relatively small number of very famous 13th-centurymappae mundi.^[15] The earliest T-O maps marked no particular geographic center and while some earlymappae mundi were specifically centered on classical sites like Delos or the Cyclades, most simply had the Mediterranean or Aegean Sea in the middle.^[16] It was only after the First Crusade that Jerusalem began to be represented as the center of the world on medieval maps, a trend which rose to prominence from the mid-12th century through the early-14th century, but was never universally observed.^[17]

The location of Paradise (the Garden of Eden) in the east of Asia is based upon theSeptuagint translation of Genesis 2:8, which describes the garden of Eden being planted in the east. This is a longstanding feature of Christian textual geographies, and while not present on the earliest T-O maps, it is a prominent feature of many earlymappae mundi, especially theBeatus maps.^[18] These depictions are often combined with a depiction of the four rivers of Paradise: the Tigris, Euphrates, Pishon and Gihon, the latter two of which were sometimes understood by medieval cartographers as the Ganges and Nile (or Geon) respectively. These were either depicted as flowing within/out from paradise and/or as four major rivers on the map.^[19]

This qualitative and conceptual type of medievalcartography could yield extremely detailed maps in addition to simple representations. The earliest maps had only a few cities and the most important bodies of water noted.^{[dubious –discuss][citation needed]}

Different cartographic material, which represented more useful tools for the traveler, were theitinerarium, which listed in order the names of towns between two points, and theperiplus that did the same for harbors and landmarks along a seacoast.^{[citation needed]}

Later maps of the T-and-O conceptual format featured many rivers and cities ofEastern as well asWestern Europe, and other features encountered during theCrusades. Decorative illustrations were also added in addition to the new geographic features. The most important cities would be represented by sketches of fortifications and towers in addition to their names, and the empty spaces would be filled with mythical creatures.^{[citation needed]}

• 
  The world map from theSaint-Sever Beatus, dating to ca. AD 1050.
• 
  From a 12th c. copy ofEtymologiae.
• 
  Map centred onDelos according toGreek tradition, from a French manuscript ofHenry of Huntingdon, late 13th century
• 
  Mappa Mundi inLa Fleur des Histoires, 1459–1463.
• 
  TheBünting cloverleaf map. A 1581 woodcut, Magdeburg.Jerusalem is in the center, surrounded by Europe, Asia and Africa.
• 
  Unknown,Mer des hystoires world map, 1491, following the model of the T-O map, centered on Jerusalem with East (the biblical location of Paradise) at the top.
• 
  On the left part of the sheet is a zonal or climatic map, communicating geographical information. On the right is a "T-O" map. ByJacobus Philippus Bergomensis.
• 
  T and O map accompanied by aV-in-square map, from a copy of theEtymologiae (c. late 8th century).
• 
  Map from theSaint Gall Isidore manuscript.
• 
  T and O map from the Flemish manuscript ofBrunetto Latini,Le Livre dou Tresor, early 14th century.

• Flat Earth, world view
• Globus cruciger
• Mappa mundi, medieval world map
• Babylonian Map of the World

• Baumgärtner, Ingrid (2001). "Die Wahrnehmung Jerusalems auf mittelalterlichen Weltkarten". In Dieter R. Bauer, Klaus Herbers and Nikolas Jaspert (eds.),Jerusalem: im Hoch- und Spätmittelalter: Konflikte und Konfliktbewältigung - Vorstellungen und Vergegenwärtigungen, pp. 271-334. Frankfurt am Main: Campus Verlag.ISBN 978-3593368511
• Crosby, Alfred W. (1996).The Measure of Reality: Quantification in Western Europe, 1250-1600. Cambridge:Cambridge University Press.ISBN 0-521-55427-6.
• Englisch, Brigitte (2002).Ordo orbis terrae. Die Weltsicht in den Mappae mundi des frühen und hohen Mittelalters. Berlin: Akademie Verlag.ISBN 3-05-003635-4
• Gautier Dalché, Patrick (2008). "L'héritage antique de la cartographie médiévale: Les problèmes et les acquis", pp. 29-66. In Richard J. A. Talbert and Richard W. Unger (eds.)Cartography in Antiquity and the Middle Ages: Fresh Perspectives, New Methods. Leiden: Brill.ISBN 9789004166639
• Lester, Toby (2009).The fourth part of the world: the race to the ends of the Earth, and the epic story of the map that gave America its name. New York, NY: Free Press.ISBN 9781416535317.
• Mauntel, Christoph (2023).Die Erdteile in der Weltordnung des Mittelalters. Asien – Europa – Afrika (Monographien zur Geschichte des Mittelalters 71) Stuttgart: Hiersemann.ISBN 978-3-7772-2311-7
• Mauntel, Christoph (2021). "The T-O Diagram and its Religious Connotations – a Circumstantial Case", in Christoph Mauntel (ed.),Geography and Religious Knowledge in the Medieval World, pp. 57-82. Berlin: deGruyter.ISBN 9783110685954
• Mode, PJ."The History and Academic Literature of Persuasive Cartography".Persuasive Cartography, The PJ Mode Collection. Cornell University Library. Retrieved22 October 2015.
• Williams, John (1997), "Isidore, Orosius and the Beatus Map",Imago Mundi,49:7–32,doi:10.1080/03085699708592856,JSTOR 1151330
• Woodward, David (1987)."MedievalMappaemundi"(PDF). In Harley, J. B.; Woodward, David (eds.).The History of Cartography. Vol. 1: Cartography in Prehistoric, Ancient, and Medieval Europe and the Mediterranean. Chicago: University of Chicago Press.ISBN 0-226-31633-5.
• Zaccagnini, Carlo (2012). "Maps of the World", in Giovanni B. Lanfranchi et al.,Leggo! Studies Presented to Frederick Mario Fales on the occasion of his 65th birthday, pp. 865–874. Wiesbaden, Harrassowitz Verlag.ISBN 9783447066594

• 7th-century maps
• Types of map
• History of cartography
• Historic maps of Asia
• Historic maps of Europe
• Maps of Africa

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