AL-TABARI WAS an indefatigable researcher and wrote many books, some of them in several volumes. As regards specifying sources in his Taʾrīkh al-rusul wa-l-mulūk, a sharp discrepancy in his approach is noticeable. Unlike the sections on Islamic history, where he gives the chain of authorities in greatest detail, for the history of pre-Islamic Iran, with the exception of Hisham ibn Muḥammad al-Kalbī (d. ca. 206/821), who is referred to sporadically, no other authority is introduced. As he himself expressly says, the discussion of the different views on the pedigree of a given king was not the kind of subject for which he had undertaken the composition of his book. He quotes his authorities with common formulas such as qāla, qīla, yaqūlu, dhukira, za ʿamū, or qāla l-Majūs, nassāba or nassābu l-Furs, ʿulamā ʾ al-Furs and the like. These all indicate that he had at his disposal a rich literature, written and oral. The sections on the Sasanians are partly based on reliable Arabic material, itself naturally derived from Middle Persian sources. Not only the Pahlavi originals but also their early Arabic renderings have been lost. The question which has been often asked but never satisfactorily answered is, how did this material reach al-Ṭabarī? I limit myself here to providing a glimpse into the richness of the historical literature on ancient Iran at the time when al-Tabari began to compile his monumental work. I am not concerned with the value of al-Tabari's work as source material for the writing of the history of the Sasanians.

One of the earliest attempts to settle the question of al-Tabari's sources was that of Theodor Nöldeke who, more than a century ago, translated the sections of his Taʾrikh on the Sasanians. He suggested that the most important general history of Iran seems to have been the Khudāynāmah, or the “Book of Kings,” that is, the Shāh-nāma of the later days. When the Pahlavi archetype was translated into Arabic for the first time by Ibn al-Muqaffa (d. ca. 140/760), it was called Kitāb siyar mulūk al-ʿajam, or simply Siyar al-mulūk. Ibn al-Muqaffaʿs translation made this important text readily accessible to a large Arabic reading public and, like many other works of this brilliant scholar, it became a celebrated book.