The influence of power conflicts on the change in the sources of Abbasid legitimacy from the beginning of the political movement to the end of Abdullah Ma'mun's Government (100-218 A.H)

Abbasids - the second dominant dynasty in the history of Islam - from the beginning of the political struggle against Umayyads to the later periods of their political life, have always relied on sources to prove their political legitimacy. At the beginning, they were able to overthrow the Umayyads and gain the government by relying on the legitimacy of their relative connection with the Prophet (PBUH). Relying on the historical data collected in a library method, this research aims to show how the change in the political alignment of the opponents of Abbasids, caused them to establish and promote the validity of their government by changing the sources they rely on for political legitimacy. Their initial association with the theory of Shi'ite legitimacy and then taking an angle with it in dealing with the new enemies, shows that the Abbasids considered their ultimate goal - preserving power - superior to any other thought and motive. The findings of this research reveal that the change in the sources of legitimacy had a direct relationship with the political alignments of the Abbasid enemies until the end of Ma'mun's caliphate. As far as possible, the information about their political enemies can be obtained from the sources used by them to instill legitimacy.