With Ibn Sa'ad, a pupil and secretary of Ibn al-Waqidi, begins a new genre which initiates biographies of Tabaqats (classes). His treatise Kitab al-tabaqat al-Kabir (the great book of classes) deals with the biographies of the Prophet (pbuh) and his companions and later dignitaries of Islam till 845.13 Ibn Sa’ad elaborates on the qualities of the Prophet (pbuh), and the main traits of his mission. It is the first major example of religious biography, universal in scope, trying to include all the religiously relevant persons of Islamic history, comprising 4,250 entries, 600 of them women.14 Ibn Sa’ad died in Baghdad in 230/845, and with his work ends the series of early, or at least comparatively early, native Arabic texts on which, for the most part, we depend for information regarding the life of Prophet Muhammed (pbuh) and the beginnings of his mission. Ibn Sa’ad’s work can be found in a Sachau edition and in others.