The year 1139 was a turning point for Roger II of Sicily. After years of bitter hostility with the Papacy and the barons of South Italy, his troops convincingly defeated the Papal armies at Galluccio and he was recognised as King of Sicily. At this time, there was a shift in Roger’s fortunes and he began to assert his authority as an autonomous Mediterranean monarch, pushing forward his vision for the kingdom. This included an ambitious building program, comprehensive reform of the state administration, as well as an attempt to extend Norman territory with attacks on North Africa and the Byzantine territories of the eastern Mediterranean. It was also at this propitious time that Roger commissioned the Muslim polymath, Muḥammad Ibn Al-Idrīsi (hereafter Idrīsi) to start work on the Book of Roger. In this paper, I argue that this timing was no mere accident but rather that the book, in particular Idrīsi’s comprehensive description of Sicily, may have been designed to play a key role in the program of administrative reform and foreign expansion undertaken by Roger post-1139.

As the seat of Roger’s government, Sicily played a strategic role in the creation of the Norman state; it was imperative that Roger and his advisors had an accurate understanding of the island and its context in relation to surrounding, and often hostile, territories. Relative to its geographical size, Idrīsi’s description of Sicily is the longest single section in the Book of Roger; the island is described settlement by settlement, spanning the entire coast and the interior. Idrīsi provides an unprecedented level of detail on toponymy, distances, fortifications, agriculture, commerce, natural resources and topography. A wide variety of superlative adjectives are used which serve to present Sicily as an abundant, verdant and prosperous place while other adjectives appear designed to demonstrate the easily defensible and impregnable state of the island’s various settlements. In short, the island of Sicily is given a centrality far beyond what would be expected for a region of its size in a standard Arabic Routes and Kingdoms text, a tradition of which the Book of Roger is very much a part.