Born approximately in 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 named Hira in the mountains for several nights of seclusion and prayer; later, at age 40, he reported being visited by Gabriel in the cave 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, similar to the other prophets in Islam.
Muhammad gained few early followers, and met hostility from some Meccan tribes. To escape persecution, Muhammad sent some followers to Abyssinia before he and his followers migrated from Mecca 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. In December 629, after eight years of intermittent conflict with 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 seized the city with little bloodshed. He destroyed 360 pagan idols at the Kaaba. In 632, a few months after returning from the Farewell Pilgrimage, Muhammad fell ill and died. Before his death, most of the Arabian Peninsula had converted to Islam.
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 (see Sharia).