The Sassanid and Byzantine Empire clashed in several battles throughout the late 6th and early 7th centuries, mainly in the two main wars that took place in 572-591 and 602-628, which weakened the two empires, ease for Arab domination.
What if the two empires did not enter so much into conflict and war and were in full force at the time Islamic expansion after death of Muhammad and the expansion of the Orthodox Caliphate?
What if the two empires did not enter so much into conflict and war and were in full force at the time Islamic expansion after death of Muhammad and the expansion of the Orthodox Caliphate?