After the death of Muhammad, Islam spread across parts of three continents as Muslim empires expanded. During the 700s and 800s, the Islamic world experienced a golden age of peace and prosperity. The early Muslim caliphs successfully united the Muslims and conquered territories through military campaigns, spreading Islam across regions of the Byzantine Empire, Persia, the Middle East, North Africa, Spain, Sicily, India, and Southeast Asia. Islamic scholars developed sharia law to help interpret the Quran and apply it to daily life, regulating various social and political aspects. The Islamic civilization made significant achievements in arts, literature, mathematics, science, and economic areas like trade and manufacturing during its golden age.