Muslim Conquests

According to traditional accounts, the Muslim conquests (Arabic: الغزوات‎, al-Ġazawāt or Arabic: الفتوحات الإسلامية‎, al-Fatūḥāt al-Islāmiyya) also referred to as the Islamic conquests or Arab conquests, began with the Islamic prophet Muhammad. He established a new unified polity in the Arabian Peninsula which under the subsequent Rashidun (The Rightly Guided Caliphs) and Umayyad Caliphates saw a century of rapid expansion of Muslim power.

They grew well beyond the Arabian Peninsula in the form of a Muslim Empire with an area of influence that stretched from the borders of China and the Indian subcontinent, across Central Asia, the Middle East, North Africa, Sicily, and the Iberian Peninsula, to the Pyrenees. Edward Gibbon writes in The History of the Decline and Fall of the Roman Empire:

Under the last of the Umayyad, the Arabian empire extended two hundred days’ journey from east to west, from the confines of Tartary and India to the shores of the Atlantic Ocean. And if we retrench the sleeve of the robe, as it is styled by their writers, the long and narrow province of march of a caravan. We should vainly seek the indissoluble union and easy obedience that pervaded the government of Augustus and the Antonines; but the progress of Islam diffused over this ample space a general resemblance of manners and opinions. The language and laws of the Quran were studied with equal devotion at Samarcand and Seville: the Moor and the Indian embraced as countrymen and brothers in the pilgrimage of Mecca; and the Arabian language was adopted as the popular idiom in all the provinces to the westward of the Tigris.

The Muslim conquests brought about the collapse of the Sassanid Empire and a great territorial loss for the Byzantine Empire. The reasons for the Muslim success are hard to reconstruct in hindsight, primarily because only fragmentary sources from the period have survived. Most historians agree that the Sassanid Persian and Byzantine Roman empires were militarily and economically exhausted from decades of fighting one another. The rapid fall of Visigothic Spain remains less easily explicable.

Jews and Christians in Persia and Jews and Monophysites in Syria were dissatisfied and sometimes even welcomed the Muslim forces, largely because of religious conflict in both empires. In the case of Byzantine Egypt, Palestine and Syria, these lands had only a few years before been reacquired from the Persians, and had not been ruled by the Byzantines for over 25 years.

Fred McGraw Donner, however, suggests that formation of a state in the Arabian peninsula and ideological (i.e. religious) coherence and mobilization was a primary reason why the Muslim armies in the space of a hundred years were able to establish the largest pre-modern empire until that time. The estimates for the size of the Islamic Caliphate suggest it was more than thirteen million square kilometers (five million square miles), making it larger than all current states except the Russian Federation.