A T and O map or T-O map, is a type of medieval world map representing the known physical world.

It was believed the world was spherical and divided in five zones. The poles were freezing and the equatorial zone was so hot, no one could pass through it. In between the poles and the middle hot zone lay two temperate zones. The T-O map represented the land mass of the northern temperate zone. It was thought that no one had ever been to the southern land mass, the antipodes, where people known as "antipodeans" lived. Theologians questioning the existing of antipodeans, reasoned by asking how Adam and Eve, the parents of all humankind, could have crossed the unbearable heat of the equator, and how would the Second Coming of Jesus manifest himself in both the northern and southern hemispheres simultaneously?

The inhabited world of the northern land mass thus mapped consisted of the three continents of Africa, Asia and Europe, with the navel of the world, umbelicus mundi, always at Jerusalem. Asia was typically the size of the other two continents combined. The land on the map is divided into three parts by a "T" shape in which Asia occupies the top of the T area, Europe the bottom left and Africa the bottom right, within the "O" of the Ocean surrounding and separating them. Thus, North is to the left and South is to the right.

The T and O style of map is sometimes called a Beatine map or a Beatus map because the one of the earliest known representations of this sort is attributed to Beatus of Liébana, an 8th century Spanish monk. The map appeared in the prologue to his twelve books of commentaries on the Apocalypse.

This qualitative and conceptual type of medieval cartography 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. The four sacred rivers of the holy land were always present. More useful tools for the traveller were the itinerary , which listed in order the names of towns between two points, and the periplus that did the same for harbours and landmarks along a seacoast.

Later maps of this same conceptual format featured many rivers and cities of Eastern as well as Western Europe, and other features encountered during the Crusades. Decorative illuminations were also added in addition to the new geographic features. The most important cities would be represented by distinct fortifications and towers in addition to their names, and the empty spaces would be filled with mythical creatures.

References

• Crosby, Alfred W. The Measure of Reality : Quantification in Western Europe, 1250-1600. Cambridge: Cambridge University Press,1996.