Simultaneouswith expansion of the Sassanid Empire there was an gradual increase in the migration of Arabs from Arabia to Oman. During the interregnum and the ensuing weakness of the Sassanid Empire, from Shahpȗr I’s death (272 A.D) to the ascend of Shahpȗr II (310 A.D), the invading hoards from the southern coasts of the Persian Gulf found new momentum in their attacks on the lands to the north of the Persian Gulf. Among the invading tribes those of Azd, Bani-tamim, Bekr-ibn-Vael, Hanzala, and Bani-taghallab were more notable. The Muslims’ conquest and the fall of the Sassanid Empire unraveled the political unity and Persian military and economic dominance over large swathes of southern and northern Persian Gulf and the Sea of Oman which, in the short term, intensified Arabism and heightened the flow of migrant from Arabia and Yemen to Bahrain, Oman and ultimately Iran. The current research seeks to study the flow of migration and settlement of various Arab tribes from the fall of the Sassanid Empire to the dawn of the Islamic era. How did Arabs manage to migrate to the southern and southeastern swathes of Iran? And, how did this bear upon the host communities? It will be concluded that notwithstanding the strengthening of Arab presence in the Persian Gulf coasts and the Sea of Oman, as a result of these migration waves, the immigrants were absorbed and assimilated into the tradition, culture and Iranian society.