The Islamic Golden Age

Within a century of the Prophet Muhammad's death in 632, Muslim rule stretched from Spain to Central Asia. The Abbasid dynasty, which took power in 750, moved the capital to a newly founded city, Baghdad, in 762. Placed on the Tigris near major trade routes, Baghdad grew into one of the largest cities in the world.

A shared language, Arabic, and a vast single market made it easy for goods, people and ideas to travel. Paper, learned from Chinese papermakers, spread across the Islamic world from the eighth century and made books far cheaper than parchment. Bookshops and libraries multiplied.

From the late eighth century, patrons in Baghdad paid scholars to translate works from Greek, Syriac, Persian and Sanskrit into Arabic. Aristotle, Galen, Euclid and Ptolemy were among the authors rendered into Arabic, often by Christian scholars such as Hunayn ibn Ishaq, who was known for careful methods of comparing manuscripts.

Translation was not simple preservation. Scholars corrected, commented on and extended the texts they received. The House of Wisdom, a library and centre of scholarship associated with the Abbasid court, has become a symbol of this effort, even though historians debate how formal an institution it was.

Al-Khwarizmi, working in Baghdad in the ninth century, wrote a book on solving equations whose title gave us the word algebra, and his name gave us the word algorithm. Through his work and others, the Indian decimal place-value system with zero spread westward. Europeans later called these Arabic numerals.

Astronomers built observatories, refined measurements of the length of the year and the tilt of Earth's axis, and improved the astrolabe, an instrument for telling time and finding the positions of stars. Many star names used today, such as Aldebaran and Betelgeuse, come from Arabic.

• Al-Razi, known in Europe as Rhazes, wrote clinical descriptions that distinguished smallpox from measles.
• Ibn Sina, known as Avicenna, wrote the Canon of Medicine, which was used as a textbook in European universities for centuries.
• Ibn al-Haytham, known as Alhazen, argued from experiments that we see because light enters the eye, and his Book of Optics influenced later European science.
• Hospitals in cities such as Baghdad, Damascus and Cairo treated patients regardless of wealth and trained physicians.

Philosophers such as al-Farabi and Ibn Rushd, known as Averroes, worked to reconcile Greek philosophy with Islamic belief. Ibn Rushd's commentaries on Aristotle were so influential in Latin Europe that medieval writers simply called him the Commentator.

At the same time, jurists developed the major schools of Islamic law, and scholars built rigorous methods for evaluating the reliability of reports about the Prophet's words and deeds. Much of this scholarship took place in mosques and, from the eleventh century, in madrasas, colleges supported by charitable endowments.

Muslim Spain, called al-Andalus, and Sicily were important bridges to Europe. In cities such as Toledo, after its capture by Castile in 1085, scholars translated Arabic works into Latin, bringing both ancient Greek learning and new Islamic contributions into European universities.

Historians often mark the end of the golden age with the Mongol sack of Baghdad in 1258, when the city was devastated and the Abbasid caliph was killed. The picture is more complicated: science and scholarship continued in Cairo, Persia, Central Asia and later the Ottoman Empire. But the Baghdad-centred world of the early Abbasids did not return.