Ibne Sa'ad's "Al-Tabaqat" is an 8 volume scholarly work covering the first two centuries of Islam. The first two volumes detail the life of the Prophet Muhammad while the remaining six volumes describe the scholarly, political, military, and religious activities of the Prophet's companions and their disciples. Considered one of the earliest and most valuable sources on the Prophet's biography, Ibne Sa'ad relied heavily on Al-Waqidi's "Al-Maghazi" as a source, especially for events during the Madinan period. The work provides a complete social picture of early Islamic society and its development over the first two centuries.