IN THE INTRODUCTION to his Taʾrikh al-rusul wa-l-mulūk (History of Prophets and Kings), al-Ṭabarī declares his intention to append to the work biographical notes on the Prophet's Companions, on the Successors, and on transmitters of subsequent generations. These notes, no doubt, constitute the work entitled Dhayl al-mudhayyal min taʾrīkh al-ṣaḥāba wa-l-tābioʿīn (The Supplement to the Supplemented: Biographies of Companions and Their Successors). It is usually referred to as Taʾrīkh al-rijāl (Biographies of Transmitters), but the title Tabaqāt (Gener- ations) is also sometimes applied to it.2 It consists of biographies, followed by a list of names and kunyas (patronyms).

In compiling a history with a biographical appendix, al-Tabarī was following the example of Yaqub ibn Sufyan al-Fasawi (d. 277/890); but he was perhaps doing so unwittingly, for al-Fasawi is mentioned neither in al-Tabarī's Taʾrīkh al-rusul wa-l-mulūk nor in his Dhayl al-mudhayyal. Al-Fasawi's book, Kitāb al-maʿrifa wa-l-ta3rīkh (The Book of Knowledge and History) consists of an annalistic history followed by biographies of Companions and Successors and ending with a list of names and kunyas.

Only one manuscript containing excerpts from Dhayl al-mudhayyal survives. That these are excerpts is indicated by the title found on the second part of the manuscript: Al-juzʾ al-thānī min al-muntakhab min kitab Dhayl al-mudhayyal min tarikh al-ṣaḥāba wa-l-tābi in taṣnif Abi Jaʿfar Muḥammad ibn Jarīr ibn Yazid al-Tabarī riwayat Abi Alī Makhlad ibn Jaʿfar ibn Makhlad ibn Sahl ibn Humrān al-Bāgarhī Canhu (The Second Part of the Excerpts (muntakhab) from the Book [called] The Supplement to the Supplemented: Biographies of Companions and Successors, Compiled by Abū Jaʿfar Muḥammad ibn Jarīr ibn Yazid al-Tabari, transmitted from him by Abu Ali Makhlad ibn Jaʿfar ibn Makhlad ibn Sahl ibn Humrān al-Baqarḥī). This title gives no indication as to the identity of the compiler of the excerpts. It may have been the transmitter Abū Ali Makhlad ibn Jaʿfar, as Loth and Rieu thought, or some transmitter of a later generation, a view preferred both by de Goeje and Rosenthal. Makhlad ibn Jaʿfar (d. 369/979–80) was accused of buying books, among them al-Tabarī's Ta'rikh al-rusul wa-l-mulūk, and transmitting them in an irregular way, namely, without having studied them with a teacher and without having acquired an authorization for transmission (ijāza).