Samaw’al composed circa 85 treatises (in Arabic). He was from a Jewish family originally from the Maghrib or from al-Andalus. His father migrated to Baghdad. Samaw’al studied Hebrew, mathematics, and medicine. He traveled in the Muslim East, eventually settling in Marāgha (northwestern Iran). He spent the rest of his life there as a physician in service of Jahān Pahlawān (d. 1186). He converted to Islam and wrote a controversial book against Judaism. His main astronomical work is Kash`awār al-munajjimīn wa-ghalaṭihim fī akthar al-a`māl wa-’l-aḥkām (Exposure of the deficiencies of the astronomers and their errors in most of [their] operations and judgments), written in 1165/1166. In this treatise, which is divided into 25 chapters (bābs), he indicates the errors that he has found in the astronomical works of the Greek scientists, such as Euclid, Archimedes, and Apollonius, of Islamic scientists such as Ibrāhīm ibn Sinān, Abū Jaˁfar al-Khāzin, Bīrūnī, Abū Ma`shar, Ḥabash, Ṣūfī, and Ibn al-Haytham, and of Indian scientists such as Brahmagupta. [BEA, Naderi]; GAS V.197