First, the migration of a number of persons belonging to the tribe of the Ash'ari from Iraq to the city of Qum towards the end of the first/seventh century, which is the period of establishment of Imamī Shī‘ism in Iran. Second, the influence of the Shī‘ī tradition of Baghdad and Najaf on Iran during the fifth/eleventh and sixth/twelfth centuries. Third, the influence of the school of Hillah on Iran during the eighth/fourteenth century.