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The early Muslim conquests or early Islamic conquests (Arabic: الْفُتُوحَاتُ الإسْلَامِيَّة, romanized: al-Futūḥāt al-ʾIslāmiyya), 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 based in Medina that expanded rapidly under the Rashidun Caliphate and the Umayyad Caliphate, culminating in Muslim rule being established on three continents (Asia, Africa, and Europe) 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."

At their height, the territory that was conquered by the Arab Muslims stretched from Iberia (at the Pyrenees) in the west to India (at Sind) in the east; Muslim control spanned Sicily, most of the Middle East and North Africa, and the Caucasus and Central Asia.

Among other drastic changes, the early Muslim conquests brought about the collapse of the Sasanian Empire and great territorial losses for the Byzantine Empire. Reasons that would provide an explanation for the Muslim victories have been difficult to reconstruct in hindsight, primarily because only fragmentary sources have survived from the period. American scholar Fred McGraw Donner suggests that Muhammad's establishment of an Islamic polity in Arabia coupled with ideological (i.e., religious) coherence and mobilization constituted the main factor that propelled the early Muslim armies to successfully establish, in the timespan of roughly a century, one of the largest empires in history. Estimates of the total area of the combined territory held by the early Muslim polities at the conquests' peak have been as high as 13,000,000 square kilometres (5,000,000 sq mi). Most historians also agree that, as another primary factor determining the early Muslim conquests' success, the Sasanians and the Byzantines were militarily and economically exhausted from decades of warfare against each other.

It has been suggested that Jews and some Christians in Sasanian and Byzantine territory were dissatisfied and welcomed the invading Muslim troops, largely because of religious conflict in both empires. However, confederations of Arab Christians, including the Ghassanids, initially allied themselves with the Byzantines. There were also instances of alliances between the Sasanians and the Byzantines, such as when they fought together against the Rashidun army during the Battle of Firaz. Some of the lands lost by the Byzantines to the Muslims (namely Egypt, Palestine, and Syria) had been reclaimed from the Sasanians only a few years prior to the Muslim conquests.