813–833) at one point nominated an Alid, Ali ibn Musa al-Rida, as his heir during the Fourth Fitna, this move was not followed up, and under Ma'mun's successors, the two families became completely estranged.[2] Of Muhammad's sons and brothers, many fled the Abbasid persecution to the remoter corners of the Caliphate, where they sometimes succeeded in establishing local dynasties, e.g. the Idrisids of Morocco, founded by Muhammad's brother Idris, or the Alavids in Tabaristan.[2][2]