Part 01 of 04 · Walls
A city inside rings
Written accounts describe a moat and more than one wall around the circle, the main wall the thickest of all. Together they drew a hard line between the caliph’s city and the world outside.
Next · Gates
01 · 750
In 750, the Abbasids overthrew the Umayyad dynasty and took control of a vast caliphate. Power was shifting east, and the new rulers wanted a capital that reflected it. They looked to Iraq, a land of old cities, near the former Sasanian capital of Ctesiphon. The question was where, exactly, to build.
02 · 762
The answer lay on the Tigris. The river and the roads around it linked the site to farmland and to trade networks reaching far beyond Iraq: a steady flow of people, supplies, and ideas. In 762, the caliph al-Mansur began to build. Geography offered the opportunity; imperial ambition would turn it into a city.
762
CE · 145 AH
The year al-Mansur founded Baghdad—the starting point of its Golden Age, in a region settled long before.
CE = Common Era · AH = Hijri year (Anno Hegirae)
The circle could not hold for long. Markets, workshops, and neighbourhoods spread beyond the original enclosure as people arrived from across the empire, drawn by work at court and by trade. Baghdad became an Arabic-speaking metropolis with a strong Persian presence, and with the people came their skills and their knowledge. Skills and ideas needed patrons, and Baghdad had them.
Under Harun al-Rashid, who ruled from 786 to 809, the court commanded immense wealth; under al-Ma’mun, from 813 to 833, translation and scholarship won prominent support. A court needed physicians and experts in calculation, and a patron surrounded by scholars gained prestige. Officials and wealthy families followed, and many of them paid for one demanding task: translation.
Patronage paid for the work. What made it last were three things: careful translation, places to keep the books, and scholars who turned what they read into new methods.
Greek, Syriac, Persian, and Sanskrit learning began to flow into Arabic. A translator had to know the subject as well as the languages, and a damaged manuscript, an unfamiliar term, or a conflicting diagram could become a puzzle in its own right. Solving those puzzles turned translators into scholars.
Books gathered in palaces, private houses, and institutions, among them the caliphal collection known as Bayt al-Hikma, the House of Wisdom. Historians still debate how it was organised; it was not a modern university. But it became a symbol of a growing culture of collectors, copyists, and readers.
In this world worked al-Khwarizmi. Writing in the early ninth century on algebra, arithmetic, astronomy, and geography, he set out systematic methods for solving equations in his Book of Algebra. “Algebra” comes from its key term, al-jabr; “algorithm” from a Latin form of his name. Two everyday words still carry his legacy.
For more than a century, Baghdad’s scholars translated, tested, and invented even as the court moved away and power shifted.
End of Period I · 762–833
In 833 al-Ma’mun died on campaign. Within three years the court had moved north to Samarra, and Baghdad would be without its caliphs for more than half a century. But what the city had gathered did not leave with them: the translators, the libraries, the new methods. In the century ahead they would be tested, argued over, and built upon.
Part I · 833–945
Between 833 and 945 the caliph’s court left Baghdad and came back. The city’s learning carried on through all of it.
The court in Samarra · 56 years

218 AH٢١٨ هـ
833
Al-Ma’mun used the state to make scholars accept one theological position. The power that paid for books could also demand agreement.
Caliph · al-Ma’mun

221 AH٢٢١ هـ
836
The caliph’s court moved about 125 km up the Tigris to a new city. Baghdad’s libraries stayed open.
Caliph · al-Mu’tasim

221–279 AH٢٢١–٢٧٩ هـ
836–892
Administrators, teachers, physicians, copyists and booksellers kept Baghdad’s learning going without the court.

279 AH٢٧٩ هـ
892
After 56 years the court returned, to a city whose learning had never stopped.
Caliph · al-Mu’tadid

334 AH٣٣٤ هـ
945
The Buyid emirs took control of Baghdad. The caliphs stayed, and so did the scholars.
Caliph · al-Mustakfi
Part II · 833–945
Baghdad’s learning was carried by people: translators who checked every manuscript, a philosopher who broke codes, engineers, and physicians who wrote at the bedside. Here are five of them.
Gathered every copy of a text before he translated it.
Translation · Medicine