This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
The Fourth Fitna was framed by contemporaries chiefly as a dynastic succession dispute rather than a doctrinal one, a rivalry between two brothers over an inheritance their own father had divided between them rather than a war fought over any single point of religious belief itself. Yet the war's aftermath carried a real and lasting religious consequence that its immediate causes had not predicted at the outset of the fighting.
Al-Ma'mun's later reign became strongly associated with state support for Mu'tazilite theology and the mihna inquisition that followed from it, a religious policy shift historians trace in part to the coalition of eastern, Persian-influenced supporters who had backed his own cause during this civil war against his brother al-Amin. The war also left the Abbasid caliphate's core territories visibly damaged, and some historians trace the caliphate's later reliance on Turkic military slaves directly to the weakened Arab military factions this civil war left behind it after Baghdad's own devastating siege. The Fourth Fitna therefore stands, in the historical record, as a war whose stated cause was a narrow family inheritance dispute but whose consequences reached into the caliphate's own religious policy and military composition for generations afterward.