Bani Abbas were the descendants of Muhammad's uncle Abbas. They used this dependence to the prophethood family well in order to achieve power and managed more than five centuries of Muslim rule as his successor. Despite the prosperity and power of the state in the first period, they gradually weakened so that the last Abbasid caliph was killed by the Mongol invasion to Baghdad in 656 Hijri and the government collapsed. Using an analytical-explanatory method, article examines the factors

more »

... g the rise and fall of the Abbasids. Since the main research concentration is investigaion of effective reasons in the rise and fall of Abbasid state, this article explains the reasons using a descriptive-analytical method by comparison of reports from former and classic references. This study uncovers that the Persians' unsparing efforts, support by parties and groups opposed to the Umayyads, regular and robust communication network between Ale Abbas and the inviters and creating a strong connection between bless Alawites and Abbasids have important roles in the rise of Abbasids. On the other hand, a change in policy towards Persians and Alawites, pushing the two groups of caliphate system, the incompetence of some caliphs and influence of Turkish element on the Abbasid caliphate causes weakness and decadence of the Abbasids.