Mecca is a city in the Makkah province of Saudi Arabia. Islamic tradition attributes the beginning of Mecca to Ishmael's descendants. Mecca is regarded as the holiest city in Islam. In the 7th century, the Islamic prophet Muhammad proclaimed Islam in the city which was by then an important trading center. As the birthplace of prophet Muhammad and a site of the composition of the Quran, Mecca is regarded as the holiest city in Islam and a pilgrimage to it known as the Hajj is obligatory upon all able Muslims.