Born in about 570 CE in the Arabian city of Mecca, Muhammad was orphaned at an early age; he was raised under the care of his paternal uncle Abu Talib. After his childhood Muhammad primarily worked as a merchant. Occasionally he would retreat to a cave in the mountains for several nights of seclusion and prayer; later, at age 40, he reported at this spot, that he was visited by Gabriel and received his first revelation from God. Three years after this event Muhammad started preaching these revelations publicly, proclaiming that "God is One", that complete "surrender" (lit. islām) to Him is the only way (dīn) acceptable to God, and that he was a prophet and messenger of God, in the same vein as other Islamic prophets.
Muhammad gained few followers early on, and met hostility from some Meccan tribes. To escape persecution, Muhammad sent some of his followers to Abyssinia before he and his followers in Mecca migrated to Medina (then known as Yathrib) in the year 622. This event, the Hijra, marks the beginning of the Islamic calendar, also known as the Hijri Calendar. In Medina, Muhammad united the tribes under the Constitution of Medina. After eight years of fighting with the Meccan tribes, Muhammad gathered an army of 10,000 Muslim converts and marched on the city of Mecca. The attack went largely uncontested and Muhammad took over the city with little bloodshed. He destroyed the pagan idols in the city and sent his followers out to destroy all remaining pagan temples in Eastern Arabia. In 632, a few months after returning to Medina from The Farewell Pilgrimage, Muhammad fell ill and died. Before his death, most of the Arabian Peninsula had converted to Islam, and he had united Arabia into a single Muslim religious polity.
The revelations (each known as Ayah, lit. "Sign [of God]") which Muhammad reported receiving until his death form the verses of the Quran, regarded by Muslims as the "Word of God" and around which the religion is based. Besides the Quran, Muhammad's teachings and practices (sunnah), found in the Hadith and sira literature, are also upheld by Muslims and used as sources of Islamic law. Muslims discuss Muhammad and other prophets of Islam with reverence, adding the phrase peace be upon him whenever their names are mentioned. While conceptions of Muhammad in medieval Christendom and other premodern contexts were largely negative, appraisals in modern history have been far more favorable.