The Islamic Golden Age refers to the period in the history of Islam, traditionally dated from the 8th century to the 13th century, when much of the historically Islamic world was ruled by various caliphates, experiencing a scientific, economic and cultural flourishing. This period is traditionally understood to have begun during the reign of the Abbasid caliph Harun al-Rashid (786 to 809) with the inauguration of the House of Wisdom  in Baghdad, where scholars from various parts of the world with different cultural backgrounds were mandated to gather and translate all of the world's classical knowledge into Arabic. It is traditionally said to have ended with the collapse of the Abbasid Caliphate with the Mongol invasions and the Sack of Baghdad in 1258, though several contemporary scholars place the end of the Islamic Golden Age around the 15th to 16th centuries.