709-775

Arab ruler, second caliph of the Abbasid dynasty, who fostered learning in astronomy and other disciplines. It was al-Mansur who began construction of the Abbasid capital at Baghdad, which replaced the old Umayyad center in Damascus as the new seat of power in the Islamic world. Once established in Baghdad, al-Mansur became an ardent patron of scholarship, encouraging translations of Greek scientific and mathematical classics into Arabic. In 773 he commissioned the translation of the sixth-century Hindu astronomical treatise Siddhanta.