The position of non-religious factors in victory of Arab Moslem in conquest of Iran

One of the most significant events in Iranian history that led to widespread change in this land is the victory of the Muslim Arabs in invading Iran. Following this important event, the Sassanid dynasty collapsed and Zoroastrianism lost its place in Iranian society, and Islam largely replaced Zoroastrianism in Iran, and it came under domination of Muslim Arabs. Because of the tremendous impact that this event has had on the life of the inhabitants of this land, this question has long been raised in the minds of many Iranians, and historians of ancient history that, as why and how the invading Muslim Arabs could rapidly defeat the Persians army and to end Sassanid dynasty. In response to this question, much research has been done and many theories have been put forward, most notably it has been emphasized over the existence of religious faith and motivation among Muslim on the one hand, and the existence of class and oppressive system among Sasanian and Zoroastrian clergy on the other. To answer this question, however, the present article attempts to extract and deduce historical data from ancient sources using a critical approach and a descriptive-analytical approach and critique of prior theories to examine the role of Iranian ruling families in the victory of the Muslim Arabs and the defeat of the Sassanid dynasty.