Abbasid Caliphate

State · 750–1259 CE · at its largest around 778 CE

The Abbasids built Baghdad into one of the world's greatest cities, where the House of Wisdom translated Greek, Persian and Indian learning. Scholars like al-Khwarizmi gave us algebra and algorithms, and the tales of the Thousand and One Nights recall the splendor of Harun al-Rashid's court.

On its lands while it lasted

Silk Road (c. 130 BCE – c. 1450 CE): A network of overland caravan routes linking China with Central Asia, Persia and the Mediterranean, along which silk, spices, horses, religions, technologies and diseases travelled for more than 1,500 years.
Umayyad Caliphate (661–750 CE): Mu'awiya I founded the Umayyad Caliphate with its capital at Damascus; it extended Muslim rule from Iberia to Central Asia.
Abbasid Caliphate (750–1258 CE): The Abbasid dynasty, descended from Muhammad's uncle, took the caliphate from the Umayyads and ruled from Iraq, presiding over the Islamic Golden Age.
Battle of Talas (751 CE): Abbasid forces defeated a Tang Chinese army near the Talas River, ending Tang expansion westward into Central Asia.
Baghdad (762 CE): Founded by the Abbasid caliph al-Mansur as a round city on the Tigris, Baghdad became the Abbasid capital and one of the largest cities in the world.
Coronation of Charlemagne (800 CE): Pope Leo III crowned Charlemagne emperor in St Peter's Basilica on Christmas Day, reviving the imperial title in the West.
Al-Khwarizmi's algebra (c. 820 CE): Al-Khwarizmi's treatise on solving linear and quadratic equations systematically founded algebra as a discipline; the word 'algebra' comes from al-jabr in its title.
House of Wisdom (c. 830 CE): An Abbasid centre of scholarship in Baghdad that flourished under Caliph al-Ma'mun, where scholars translated Greek, Persian and Indian works into Arabic.
Cyrillic script (c. 893 CE): Scholars in the First Bulgarian Empire, probably at Preslav, built a Slavic alphabet mainly from Greek letters; Cyrillic now writes Russian, Ukrainian, Bulgarian, Serbian and many more.
Founding of the Holy Roman Empire (962 CE): Pope John XII crowned Otto I emperor in Rome, the conventional start of the Holy Roman Empire, which lasted until 1806.
Cairo (969 CE): The Fatimid general Jawhar founded al-Qahira beside Fustat after conquering Egypt; it grew into the largest city of the Arab world.
Avicenna (c. 980 CE – 1037 CE): A Persian physician and philosopher, author of The Canon of Medicine and The Book of Healing, one of the most influential thinkers of the Islamic Golden Age.
Book of Optics (c. 1011 CE): Ibn al-Haytham's Book of Optics showed that vision occurs when light enters the eye and described experiments with the camera obscura; it deeply influenced later European optics.
First Crusade (1096–1099 CE): Answering Pope Urban II’s call, armies of western knights marched to Constantinople, crossed Anatolia, took Antioch after a long siege and captured Jerusalem in July 1099, founding the crusader states.
Mongol sack of Baghdad (1258 CE): Mongol forces under Hulagu Khan captured and sacked Baghdad, killing the last Abbasid caliph in Baghdad and ending the Abbasid Caliphate there.