The Islamization of Iran occurred as a result of the Arab conquest of Persia. The institution of a new culture, especially if the new culture is being installed by one less organized or less capable than the culture being displaced, is a struggle with an unpredictable outcome. Depending on the resilience of the conquered culture, it may take a few centuries. Often, however, it has been the case that the conquering culture is weakened to the point of being absorbed by the people it had conquered. The struggle of the Arab caliphs, the Umayyads and the Abbasids, against the mighty forces in Iran, Khorasan, and Transoxania is a case in point. It was a very tedious Islamic takeover that gradually won over the acceptance of the inhabitants in Persia at the time. However, this process of assimilation was not new in the area as many Iranians had previous traditions to which they had adapted during pre-Islamic times of the Achaemenids, Parthians and Sassanians. These two customs, then, were merged together to form what we now call the Iranian Islamic identity.
This merger transformed much of the cultural, scientific and political structures of Iran and its society; from the blossoming of Persian literature to strengthening of science and philosophy. These became major elements of the tradition in Iran since that time. Inherent was also the heritage of thousands of years of Persian civilization which created these sorts of "cultural highways" and