Byzantine Empire

State · 633–1453 CE · at its largest around 633 CE

The Christian Roman Empire of the Greek-speaking east, ruled from Constantinople, a city of domes, mosaics, icons and silk. It preserved Roman law and ancient Greek learning for later ages and carried Orthodox Christianity and writing to the Slavs.

On its lands while it lasted

Battle of the Yarmuk (636 CE): Arab Muslim armies decisively defeated the Byzantine army near the Yarmuk River, opening the Levant to the Muslim conquest.
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.
Battle of Karbala (680 CE): Husayn ibn Ali, grandson of Muhammad, and his small party were killed by Umayyad forces at Karbala, an event central to Shia Islam and commemorated on Ashura.
Dome of the Rock (c. 691 CE): Built on Jerusalem's Temple Mount under the Umayyad caliph Abd al-Malik, it is the oldest surviving major work of Islamic architecture.
Trans-Saharan trade (c. 700–1600 CE): Camel caravans crossed the Sahara between Morocco and the Niger bend, exchanging North African goods and Saharan salt from mines such as Taghaza for West African gold, enriching the empires of Ghana, Mali and Songhai.
Umayyad conquest of Hispania (711–718 CE): Umayyad forces under Tariq ibn Ziyad crossed from North Africa and conquered most of the Visigothic kingdom within a few years.
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.
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.
Council of Clermont (1095 CE): Pope Urban II called on Western Christians to aid Byzantium and take Jerusalem, launching the First Crusade.
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.
Founding of the Ottoman state (c. 1299 CE): Osman I, leader of a Turkish principality in northwestern Anatolia, founded the dynasty whose state grew into the Ottoman Empire, which lasted until 1922.
Black Death (1346–1353 CE): Bubonic plague pandemic that reached Europe through Mediterranean ports such as Messina in 1347 and killed an estimated third to half of Europe's population.
Leonardo da Vinci (1452 CE – 1519 CE): Italian Renaissance polymath born in Vinci, painter of the Mona Lisa and The Last Supper, whose notebooks record studies in anatomy, engineering and flight.
Fall of Constantinople (1453 CE): Ottoman Sultan Mehmed II captured Constantinople, ending the Byzantine Empire; the city became the Ottoman capital.