Over the years, Iranians have been able to create special patterns in architectural advances in the construction of their temples. But the type of tribal life of the Arab caused the invading Muslims to create their own architectural art and often take more advantage of the architecture of the conquered lands to create various new buildings. Due to this, we see many similarities and similarities between Iranian buildings in the first few centuries of the Islamic era with Sassanid architecture. One of the measures taken by the Arab conquerors to accelerate the spread of the new religion among the inhabitants of Iran was to change the function of a number of Sasanian buildings to buildings with new uses in the Islamic era. The question related to the reason for this change of use from one period to another is answered. It is assumed that, most likely, the neo-Muslim Iranian, with this tactic, protected their important religious sites from widespread destruction and even in some cases used them as a burial place for national celebrities and prominent Iranian figures. The results of the present study made it clear that the change of use of some Sasanian buildings to Islamic religious buildings generally occurred in the second half of the first century AH/ 7 AD and with the intensification of the destruction of Iranian shrines by the Arab.