Muslim conquests
The first Muslim conquests (632–732), (, Fatah, literally opening,) also referred to as the Islamic conquests or Arab conquests, began after the death of the Islamic prophet Muhammad. He established a new unified political polity in the Arabian peninsula which under the following Rashidun and Umayyad Caliphates saw a century of rapid expansion of Arab power well beyond the Arabian peninsula in the form of a vast Muslim Arab Empire with an area of influence that stretched from northwest India, across Central Asia, the Middle East, North Africa, southern Italy, and the Iberian Peninsula, to the Pyrenees. The Arab conquests culminated in Islamic rule being established across three continents (Asia, Africa, and Europe). 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."The Arab conquests brought about the collapse of the Sassanid Empire and a great territorial loss for the Byzantine Empire. Though spectacular, the Arab successes are not hard to understand in hindsight. The Sassanid Persian and Byzantine empires were militarily exhausted from decades of fighting one another. This prevented them from dealing effectively with the mobile Arab raiders operating from the desert. Moreover, many of the peoples living under the rule of these empires, for example Jews and Christians in Persia and Monophysites in Syria, were disloyal and sometimes even welcomed the Arab invaders, largely because of religious conflict in both empires.