Early discussions about the identity of al-Mahdi by religious scholars can be traced back to the time after the Second Fitna. These discussions developed in different directions and were influenced by traditions (hadiths) attributed to Muhammad. In Umayyad times, scholars and traditionists not only differed on which caliph or rebel leader should be designated as Mahdi, but also on whether the Mahdi is a messianic figure and if signs and predictions of his time have been satisfied. By the time of the Abbasid Revolution in the year 750, Mahdi was already a known concept. Evidence shows that the first Abbasid caliph As-Saffah assumed the title of "the Mahdi" for himself.