Tabari was some fifty years old when al-Mu'tadid became caliph. He was well past seventy in the year his "History" was published. During the intervening years, he was famous, if somewhat controversial, personality. Among the figures of his age, he had access to sources of information equal to anyone, except, perhaps, those who were directly connected with decision making within the government. Most, if not all, the materials for the histories of al-Mu'tadid, al-Muktafi, and the early years of al-Muqtadir were collected by him about the time the reported events took place. His accounts are as authentic as one can expect from that period. Tabari final years were marked by conflict with the Hanbalite followers of Al-Hasan ibn 'Ali al-Barbahari, a student of the students of Ibn Hanbal. Tabari was known for his view that Hanbalism was not a legitimate school of thought, as Ibn Hanbal was a compiler of traditions and not a proper jurist. The Hanbalites of Baghdad would often stone Tabari's house, escalating the persecution to the point where Abbasid authorities had to subdue them by force. The Baghdad chief of police tried to organize a debate between Tabari and the Hanbalites to settle their differences. While Tabari accepted, the Hanbalites did not show up but instead came later to pelt his house with stones again. The constant threat of violence from the Hanbalites hung over Tabari's head for the rest of his life.