From Mecca to the Pyrenees
1Islam began in the Arabian city of Mecca in the early 600s. Muslims believe that, starting about 610, God revealed messages to the merchant Muhammad, and that these messages form the Quran. Muslims believe in one God and follow duties known as the Five Pillars: declaring their faith, praying five times a day, giving to people in need, fasting during the month of Ramadan, and making the hajj, a pilgrimage to Mecca, once in a lifetime if they are able. By Muhammad's death in 632, most of Arabia had joined the Muslim community.
2The caliphs who led Muslims after him sent Arab armies beyond Arabia. The Byzantine and Persian empires had just fought each other for more than twenty years, and both were worn out. Within about twenty years, Arab armies took Syria, Egypt and most of Persia. In 711 a force under Tariq ibn Ziyad crossed from North Africa into Spain, which Muslims called al-Andalus. Muslim rulers would govern parts of al-Andalus for nearly 800 years. Many Christians and Jews in the conquered lands kept their own faith and paid a special tax, and many people became Muslims only slowly, over generations.
3Muslim cities became centers of learning. Al-Biruni used a mountain and careful angle measurements to estimate the size of the Earth. In Córdoba, the surgeon al-Zahrawi wrote a guide to surgery with drawings of about 200 instruments. In the 1200s, Ibn al-Nafis described how blood travels from the heart through the lungs and back. Large hospitals in cities such as Baghdad, Damascus and Cairo treated patients, often free of charge. Astronomers improved the astrolabe, a tool for measuring the height of stars to find the time and a traveler's position.
4Trade tied this world together. Merchants crossed deserts with camel caravans and sailed the Indian Ocean in ships called dhows. In city markets, an inspector called the muhtasib checked that scales and measures were honest. Goods, books and ideas moved from Spain to India along the same routes.