civil unrest gradually caused instability within the empire under Umayyad dynasty because many muslims were unhappy with : The emphasis on politics and growing power of Arab Rulers
Back then, there were a Tension between the Muslims that came from Persian Lineage and The one that came from Arab Lineage. The Arabian felt that they were the chosen lineage that is blessed by the God, and it's very hard for the Persian to gain political power during that period
hope this helps
