Abu ʿAlī Aḥmad b. ʿUmar Ibn Rusta was born in Isfahan at an unknown date and he flourished in the first decade of the 10th century CE. Only the seventh volume of his Kitāb al-Aʿlāq al-nafīsa has survived. The work deals with mathematical, descriptive and human geography and a variety of historical and other subjects. One of his sources seems to have been a more complete version of Ibn Khurradādhbih, which has not survived. The Kitāb al-Aʿlāq al-nafīsa, which has been characterized as an encyclopedia of geographical knowledge, is a rich source on the kinds of subjects that interested the cultivated classes of ʿAbbāsid society.