A native of Malaga, of royal blood, and a lineal descendant of Mohammed, he united to pride of birth and the advantages of fortune all the learning and all the accomplishments to be acquired in an enlightened age.
Quoted from S.P. Scott: History of the Moorish Empire in Europe; 3 vols; J.B. Lippincott Company, 1904. pp 461-2:
The reputation of all mediaeval geographers, however distinguished, was obscured by the fame of the great Idrisi. A native of Malaga, of royal blood, and a lineal descendant of Mohammed, he united to pride of birth and the advantages of fortune all the learning and all the accomplishments to be acquired in an enlightened age. His relationship to the Prophet invested him with a dignity and an importance second to none, in the sight of every devout Mussulman. His education at Cordoba was the best that the ancient capital of the khalifs, still the intellectual centre of the world, could afford. His mind, improved by travel, was familiar with many countries whose physical features he afterwards depicted with such ability.
Invited to Palermo by Roger, King of Sicily, he speedily attained a high rank among the scholars of that brilliant court. The geography he composed, partly from his own information, partly from data furnished by the King, who had long made a study of that science, represented the labour of fifteen years.
In vividness of description, in accuracy of detail, in correct estimation of distances, it is one of the most remarkable literary productions of mediaeval times. [Before that], the incomplete [geographical] work of Ptolemy had for centuries been the recognized, indeed the only, authority. The configuration of the earth's surface, its climates, the locations of continents and seas, of cities and empires, were facts little known, even to persons of the best education. In Christian lands the Church sedulously discouraged all such studies as inimical to Scriptural revelation…
The compilation of Idrisi marks an era in the history of science. Not only is its historical information most interesting and valuable, but its descriptions of many parts of the earth are still authoritative. For three centuries geographers copied his maps without alteration. The relative position of the lakes which form the Nile, as delineated in his work, does not differ greatly from that established by Baker and Stanley more than seven hundred years afterwards, and their number is the same. The mechanical genius of the author was not inferior to his erudition. The celestial and terrestrial planisphere of silver which he constructed for his royal patron was nearly six feet in diameter, and weighed four hundred and fifty pounds; upon the one side the zodiac and the constellations, upon the other-divided for convenience into segments-the bodies of land and water, with the respective situations of the various countries, were engraved. As a recompense for his skill, Idrisi received [a reward] from King Roger… amounting to a hundred thousand pieces of silver, and a ship laden with valuable merchandise. Such was the munificence with which the son of a Norman freebooter, bred to arms and rapine and ignorant of letters, rewarded the genius of a scholar whose race was stigmatized by every Christian power in Europe as barbarian and infidel.