The Abbasid Caliphate or Abbasid Empire was the third Islamic caliphate, ruled by the Abbasid dynasty. The dynasty was descended from Muhammad's uncle, Abbas ibn Abd al-Muttalib (d. 653), after whom it is named. The Abbasids rose to power in 750, when the Abbasid Revolution overthrew the preceding Umayyad Caliphate, and they ruled as caliphs from their metropole in Iraq until 1258, with Baghdad as their capital for most of their history. The Abbasid Revolution had its origins and first successes in the easterly region of Khurasan, far from the Levantine center of Umayyad influence. The Abbasids first centered their government in Kufa, Iraq, but in 762 the second caliph al-Mansur founded the city of Baghdad and made it the capital. Baghdad became a center of science, culture, arts, and invention, ushering in what became known as the Golden Age of Islam. It hosted several key academic institutions, such as the House of Wisdom, as well as a multi-ethnic and multi-religious population, which made the city famous as a centre of learning across the world. The Abbasid period was marked by the use of bureaucrats in government, including the vizier, as well as a growing inclusion of non-Arab Muslims in the ummah (Muslim community) and among the political elites. The height of Abbasid power and prestige is traditionally associated with the reign of Harun al-Rashid (r. 786–809).