Founded by the Prophet Mohammed in 570 AD, Islam literally means submitting to the will of god. Muslims believe that when the Prophet was meditating in a cave on Mount Hira, near Mecca, the archangel Gabriel came to him and told him that there is one God but Allah and that Mohammed should become the messenger to carry out God's will and convey God's ideas to people. When Mohammed first began to preach he had difficulty in attracting followers, and the rulers of the city attempted to silence him, as they feared his preaching contradicted and threatened their profitable kaaba-based religion. In AD 622, the Prophet with his followers fled to the town of Yathrib (later renamed Medina). This flight, called the Hijra, marks the start of the Islamic calendar.