850

By place

Europe

• February 1 – King Ramiro I dies in his palace at Santa María del Naranco, after an 8-year reign. He is succeeded by his son Ordoño I, as ruler of Asturias.
• Danish Viking raiders, led by King Rorik, conquer Dorestad and Utrecht. Emperor Lothair I recognizes him as ruler of most of Friesland.
• King Louis II, the eldest son of Lothair I, is crowned joint emperor by Pope Leo IV at Rome, and becomes co-ruler of the Middle Frankish Kingdom.

Britain

• King Kenneth I of Alba invades Northern Northumbria during the period of 850–858, burning Dunbar and Melrose.
• The Pillar of Eliseg is erected by King Cyngen ap Cadell of Powys, as a memorial to his great-grandfather Elisedd ap Gwylog .

Middle East

• The Abbasid caliph al-Mutawakkil issues a decree that orders Jews and Christians to wear the zunnar, honey-coloured outer garments and badge-like patches on their on their servants' clothing.

Japan

• May 6 – Emperor Ninmyō dies after a 17-year reign. He is succeeded by his son Montoku, as the 55th emperor of Japan.

India

• It is hypothesized that sometime around 850 a group of Buddhist pilgrims travelling through a valley near Roopkund were killed when caught out in the open in a sudden hailstorm. Their remains were discovered in 1942.

Mesoamerica

• Uxmal becomes the capital of a large state in the Puuk hills region of northern Yucatán. The city is connected by causeways to other important Puuk sites, such as K'abah, Sayil, and Labna.

By topic

Food and Drink

• Coffee is discovered by the Ethiopian goatherder Kaldi in East Africa, who notices that his goats become energetic after chewing the red berries from certain wild bushes.

Religion

• April 22 – Gunther becomes archbishop of Cologne.
• June 18 – Perfecto, a Christian priest in Muslim Córdoba, is executed after he refuses to retract critical comments he made about Muhammad.