1) During the early Islamic empires, Muslims preserved knowledge from the Byzantine and Persian empires and began collecting knowledge from places like India and China. 2) The Islamic Golden Age began during the Abbasid Caliphate when the capital was moved to Baghdad, which became a major center of learning under Caliph Harun al-Rashid. 3) Islamic scientists and scholars made major advances in fields like mathematics, astronomy, medicine, and philosophy by translating ancient Greek, Sanskrit, Chinese, and Persian works and collecting knowledge in libraries in Baghdad and other cities.