The Arab ascendancy, or Muslim conquests from 600-800 CE, involved the rapid expansion of a new Islamic empire across the Middle East, North Africa, and parts of Europe, starting after the death of Muhammad in 632 CE. This expansion was fueled by religious fervor, political ambition, and economic opportunity, leading to the swift conquest of the Sasanian Empire and vast territories from the Byzantine Empire, including Syria, Egypt, Persia, and eventually reaching as far as the Iberian Peninsula and China.