I want to know the answer to the following question:
Which Arab Caliphate defeated Iran first?
All the background I'm provided with is that "The prolonged Byzantine-Sassanid Wars, most importantly the climactic Byzantine-Sassanid War of 602-628, as well as the social conflict within the Sassanid Empire, opened the way for an Arab invasion to Iran in the 7th century.". Is that enough to answer the question?