Answer
Baghdad flourished under al-Ma'mun's patronage. As the capital of the Abbasid Caliphate, Baghdad became a center of learning and culture during al-Ma'mun's reign. He established the House of Wisdom, a library and academy that attracted scholars from around the world. Baghdad also became a major trading hub, connecting the East and West. Under al-Ma'mun's rule, Baghdad became one of the most important cities in the Islamic world.