WebHārūn al-Rashīd , (born March 763 or February 766, Rayy, Iran—died March 24, 809, Ṭūs, Iran), Fifth caliph of the ʿAbbāsid dynasty. Neither a great ruler nor a prepossessing character, Hārūn ruled (786–809) at a time when Islamic society reached its zenith in terms of wealth, learning, and power.