the thirty-fifth, and I would not be surprised if the fourteenth volume were to contain five strata when we compare it with the other volumes.

Muslim writers have employed this method of presenting biographies since the early days of scholarly activity. In Rosenthal’s view, it is an authentically Islamic classification and may well represent the earliest chronological scheme to appear in Islamic historical thought. It was not the product of external influences; rather, it arose naturally from the idea of the Companions of the Messenger of Allah, then the Successors, and so on. (1)

Supporting this is the hadith reported by al-Bukhari: “The best of my community is my generation, then those who follow them, then those who follow them.” (2) Al-ʿAynī commented that the best of generations are the Companions, then the Successors, then the Successors of the Successors. (3)

This concept is plainly evident in the works of Imam Ibn Ḥibbān al-Bustī (d. 354 AH), who in his books al-Thiqāt and Mashāhir ʿUlamāʾ al-Amṣār divided the transmitters into three strata: the Companions, the Successors, and the Successors of the Successors. Here, therefore, a ṭabaqa came to mean a generation.

Some scholars attempted to give the ṭabaqa a clear temporal span, with some setting it at twenty years (4), others at forty years (5), and so forth.