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 (later Byzantine) and Sasanian empires. Various vassal kingdoms and allied nomadic nations in the form of buffer states and proxies also played a role. The wars were ended by the Arab 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.