The 3rd and 4th centuries of Hijri were the era of expansion of the Shiites in the lands under the rule of the Abbasid Caliphate, and the eastern lands of this Caliphate, i.e. cultural Iran, also witnessed many changes during this period, such as the formation of the Alawite governments of Tabaristan and Al-Buyeh, uprisings and movements, as well as the Ismaili da'wah and the spread of Imamiyya ideas. It has been in line with the generalization and expansion of Shi'ism. However, from the fourth century onwards, the opportunity for the continuation of this dynamic and the struggle of the Shiites and their roles in the social and political atmosphere of Iran was stopped to such an extent that the reason for this stop as a research issue, the necessity of studying the obstacles in front of this process and the lack of continuity of these currents. explores. The investigation of the obstacles on the way to the expansion of Shiism in this research is done based on the framework of Hager Strand's diffusion theory in order to obtain qualitative and quantitative information in this regard and to categorize the most influential ones in this historical expansion.