structural:summarization, stylistic:tone
Religion

Even though the Safavids were not the first Shiʻi rulers in Iran, they played a crucial role in forcefully making Shiʻa Islam the official religion in the whole of Iran, as well as what is nowadays the Republic of Azerbaijan. There were large Shiʻi communities in some cities like Qom and Sabzevar as early as the 8th century. In the 10th and 11th centuries the Buwayhids, who were of the Zaidiyyah branch of Shiʻa Islam, ruled in Fars, Isfahan and Baghdad. As a result of the Mongol conquest and the relative religious tolerance of the Ilkhanids, Shiʻi dynasties were re-established in Iran, Sarbedaran in Khorasan being the most important. The Ilkhanid ruler Öljaitü converted to Twelver Shiʻism in the 13th century.