The Roman–Persian Wars, also known as the Roman–Iranian Wars, were a series of conflicts between states of the Greco-Roman world and two successive Iranian empires: the Parthian and the Sasanian. Battles between the Parthian Empire and the Roman Republic began in 54 BC; wars began under the late Republic, and continued through the Roman and Sasanian empires. A plethora of vassal kingdoms and allied nomadic nations in the form of buffer states and proxies also played a role. The wars were ended by the early Muslim conquests, which led to the fall of the Sasanian Empire and huge territorial losses for the Byzantine Empire, shortly after the end of the last war between them.

The early Muslim conquests or early Islamic conquests, also known as the Arab conquests, were initiated in the 7th century by Muhammad, the founder of Islam. He established a new unified polity in Arabia that expanded rapidly under the Rashidun Caliphate and the Umayyad Caliphate, culminating in Muslim rule being established on three continents over the next century. According to Scottish historian James Buchan: "In speed and extent, the first Arab conquests were matched only by those of Alexander the Great, and they were more lasting."