Diagrammatic T-O map. The world portrayed as a circle divided by a T shape into three continents, Asia, Europe, and Africa. At the base of the circle is Gades. A T and O map or O-T or T-O map (orbis terrarum, orb or circle of the lands; with the letter T inside an O), is a type of medieval world map, sometimes also called a Beatine map or a Beatus map because one of the earliest known representations of this sort is attributed to Beatus of Li矇bana, an 8th century Spanish monk. The T is the Mediterranean, the Nile, and the Don (formerly called the Tanais) dividing the three continents, Asia, Europe and Africa, and the O is the encircling ocean.