Ibn Isḥāq was a Tunisian astronomer who left an unfinished zīj with a few canons and instructions for their use; this marked the first of a family of Maghribī astronomical works of this kind.  The zīj was heavily influenced by Ibn al-Zarqālī (d. 1100), and therefore characteristically contained sidereal mean motion tables, a model for the trepidation of the equinoxes, a solar model with variable eccentricity, and Zarqālī’s correction of the Ptolemaic lunar model as well as some of his parameters. Before Ibn Isḥāq, we only know for the Maghrib that at the beginning of the 11th c Ibn Abī al-Rijāl al-Qayrawānī composed a zīj which has been lost. Until recently the only known references to Ibn Isḥāq were from: 1) the famous historian Ibn Khaldūn (1332–82), who says, in his Muqaddima, that he was an astronomer at the beginning of the 13th century who composed his zīj using (his own) observations as well as the information he obtained through correspondence with a Sicilian Jew who was competent in Astronomy and a good teacher; and 2) Ibn al-Bannā’ al-Marrākushī (1256–1321) who states in his Minhāj al-ṭālib fī ta`dīl al-kawākib that Ibn Isḥāq made observations in Marrakech, that his book was written on cards or independent sheets (baṭā’iq), and (in one manuscript) that some of his tables were calculated for year 1222. Much more information on Ibn Isḥāq has been gathered due to the discovery, by D. A. King, of Hyderabad, Andhra Pradesh State Library MS 298, copied in Homs (Syria) in 1317, which contains the most important collection of materials derived from Ibn Isḥāq as well as from other (mainly Andalusian) sources. The zījes derived from Ibn Isḥāq were used in the Maghrib until the nineteenth century, for they allowed the computation of sidereal longitudes that were used by astrologers. [BEA, Samsó]