Basra Grand Mosque was one of the Islam world political and cultural institutions in the first two centuries (A.H.). The main question here is that with regards to the presence of new Muslims and Mawālīs in the city of Basra, what the status and role of Basra Grand Mosque was in the development of Islam cultural and religious foundations and how this Grand Mosque interacted with the Grand Mosque of Kufa. In response, we examine the theoretical definition, the scope and the comprehensiveness of the mosque in the cities. The process of the formation of Basra Grand Mosque and its cultural and scientific richness will also be investigated implementing historical and geographical sources. Eventually, the interactions between Basra Grand Mosque and Kufa Grand Mosque will be examined. Although military and political imperatives led to the establishment of Basra Grand Mosque, this place became the main center for the development of cultural and scientific principles among new Muslims and resulted in the emergence of theology, syntax and freedom of Islamic thought.