By Gerhard Dohrn-van Rossum
World and Global History: Research and Teaching, edited by Seija Jalagin, Susanna Tavera and Andrew Dilley (Pisa, 2011)
Introduction: Working for eighteen years under the patronage of the Norman King Roger II Guiscard of Sicily, who gathered scholars from many regions at his court in Palermo, the Moroccan geographer Al-Idrīsī in 1154 completed a description and an atlas of maps of the known world. Officially titled Entertainment for those wanting to discover the world (or A Diversion for the Man Longing to Travel to Far-Off Places), the text was generally known as The Book of Roger (Arabic: Kitab Rujar) and the maps as Tabula Rogeriana. According to modern standards, it was the best cartographical work and the richest source of geographical information produced during the Middle Ages.