Ahmad ibn Rustah Isfahani;
(Persian: احمد ابن رسته اصفهانی Aḥmad ibn Rusta Iṣfahānī), more commonly known as Ibn Rustah (ابن رسته, also spelled Ibn Rusta and Ibn Ruste), was a 10th-century Persian explorer and geographer born in Rosta district, Isfahan, Persia. He wrote a geographical compendium known as Book of Precious Records. The information on his home town of Isfahan is especially extensive and valuable. Ibn Rustah states that, while for other lands he had to depend on second-hand reports, often acquired with great difficulty and with no means of checking their veracity, for Isfahan he could use his own experience and observations or statements from others known to be reliable. Thus we have a description of the twenty districts (rostaqs) of Isfahan containing details not found in other geographers’ works. Concerning the town itself, we learn that it was perfectly circular in shape, with a circumference of half a farsang, walls defended by a hundred towers, and four gates.