Al-Istakhri, who flourished about the year A.D. 951, obtained his name from Istakhar (_i.e._, Persepolis), where he was born. He was a traveller whose geographical work has been translated into German by Mordtmann. When Istakhari was in the Indus Valley he met another celebrated traveller, Ibn Haukul, whose book Sir William Ouseley translated in A.D. 1800 into English, under the title of 'The Oriental Geography of Ibn Haukul.' Haukul, who died A.D. 976, had travelled for nearly twenty-eight years in the countries of Islam with the works of Ibn Khordabeh and Jeihani in his hands, and his work, which bears the generally approved title of 'Highways and Countries,' is based on the book of Istakhri. But the greatest geographer and naturalist of this period is Abu Raihan Al-Beruni (born about A.D. 971), who accompanied Mahmud the Ghaznavide on his invasions to India. He was to Mahmud of Ghazni what Aristotle was to Alexander, with the difference, however, that he actually accompanied the conqueror on his Indian campaigns. He travelled into different countries and to and from India for the space of forty years, and during that time was much occupied with astronomy and astronomical observations, as well as geography. His works are said to have exceeded a camel-load, but the most valuable of all of them is his description of India. It gives an account of the religion of India, its philosophy, literature, geography, chronology, astronomy, customs, law and astrology about a.d. 1030, and has been edited by Edward Sachau, Professor in the Royal University of Berlin. An English edition, containing a preface, the translation of the Arabic text, notes and indices, has also been published. Al-Beruni died at Ghurna A.D. 1038. He used to correspond with Avicenna, who was his contemporary, and who gives in his works the answers to the questions addressed to him by this famous geographer, astronomer, geometrician, historian, scholar, and logician. Some years later Abu O'beid Abd-Allah Al-Bekri distinguished himself as one of the greatest geographers, with whose labours Quatremere and Dozy and Gayangos have made us better acquainted. He was, by birth, from Andalusia, whence also many others travelled to the East, either for instruction or for trade or as pilgrims, and of whom about a couple of dozen are mentioned by Makkari. Some of these gave descriptions and topographies, to which class of literature also the poetical laudations of celebrated towns belong. Not only Baghdad, Damascus, Cairo, Fez, Morocco and Khairwan were praised or satirized, but also Cordova, Seville, Granada, Malaga, Toledo, Valencia and Zohra were described in Arabic poems. Al-Bekri died in A.D. 1094-1095, and was followed by Idrisi, the author of a work on Arabian geography of some celebrity, and which has been translated into Latin. He died A.D. 1164.