Islam emerged in the Arabian Peninsula in 610 AD when Muhammad, an Arab merchant living in the city-state of Mecca in current day Saudi Arabia, announced his mission as the Messenger of God. Still during his lifetime, the Arabs accepted his call. Within a century, the Islamic world extended from the borders of France to the Indian subcontinent. Schism came early when Muslims disputed the right to leadership of the Muslim community and divided into followers of the Sunni and the Shi'a traditions. The message of God, collected in the Koran, and the model behaviour of the Prophet Muhammad, as interpreted by medieval scholars, became the body of law Muslims still recognize. Today, Muslim modernists and radical Islamists agree that Islamic law needs to be reinterpreted. It includes biographies of individuals who have influenced the interpretation of Islamic dogma, politics, and culture from earliest days of the religion to the present day. Further entries are on major sects, philosophical trends, and the responses by Islamic movements to issues of 21st century politics, such as inroads of Westernisation in the Islamic world and radical Islam's terrorist extremists.