IN 1969 P. FORAND published the fruits of his reading of Yazid ibn Muḥammad al-Azdi's Ta'rikh al-Mawṣil, at this point only available to him on a film of the Chester Beatty manuscript. Although chiefly interested in reconstructing some of the administrative history of the city during the late Umayyad and early Abbāsid period, Forand concluded with some historiographic comparisons, principally between al- Azdī and his more celebrated Mosuli successor, Izz al-Din ibn al-Athīr. He also had something to say about al-Azdī and his contemporary, al-Tabari. Noting that al-Azdī's isnāds often begin with the same au- thorities cited by al-Tabari in his Taʾrikh al-rusul wa-l-muluk, only to diverge later on, he proposed that neither was copying from the written work of the other. The significance of this, for the study of early Muslim historiography, has yet to be studied in detail”. In fact, aside from A. Habība's comments in the introduction to his edition of the Taʾrīkh, which appeared just as Forand's article was being published, nothing of detail has been said of al-Azdī and his work, much less of his handling of isnāds and his sources more generally. For all that the work has been praised, and also put to use in several studies on early ʿAbbāsid politics, it has not been properly studied.

As far as our understanding of al-Ṭabarī is concerned, the neglect is unfortunate for at least three reasons. First, we shall shortly see that the Taʾrikh al-Mawṣil was written in the 320s or very early 330s, and that al-Azdi was familiar with al-Ṭabarī's work; it is thus an extremely early witness to the history of al-Ṭabarī's text-indeed much earlier than the sources that are customarily pressed into service to improve our understanding of the Taʾrikh al-rusul wa-l-mulūk, e.g. Ibn Misk- awayh, Ibn Asākir, Ibn al-Athir, and Ibn Khallikän. Second, since al-Azdī was writing in the decades following al-Tabari, his work can say something about the reception of al-Ṭabarī's work among those who immediately followed him. That al-Ṭabarī is significant we can all agree; but about precisely how he became so significant there is no clear consensus. Third-and now returning to Forand's insight-al-Azdī frequently drew on the same authorities tapped by al-Ṭabarī, but whose works are for the most part lost, such as Abū Maʿshar (d. 170/786), Abū Mikhnaf (d. 157/774), al-Haytham ibn Adi (d. 207/822), al- Madā'inī (d. 228/843), and “Umar ibn Shabba (d. 264/877).