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.[2]
It is hypothesized that sometime around 850 a group of Buddhist pilgrims travelling through a valley near Roopkund (modern India) were killed when caught out in the open in a sudden hailstorm. Their remains were discovered in 1942.
Uxmal becomes the capital of a large state in the Puuk hills region of northern Yucatán (modern Mexico). The city is connected by causeways (sakbe) to other important Puuk sites, such as K'abah, Sayil, and Labna (approximate date).
Coffee is discovered (according to legend) by the Ethiopian goatherder Kaldi in East Africa, who notices that his goats become energetic after chewing the red berries from certain wild bushes (approximate date).
Suleiman al-Tajir, Muslim merchant and traveller, visits China during the Tang Dynasty. He observes the manufacturing of Chinese porcelain at Guangzhou, and writes of his admiration for its transparent quality. Suleiman also describes the mosque at Guangzhou, its granaries, its local government administration, some of its written records, and the treatment of travellers, along with the use of ceramics, rice wine, and tea (approximate date).
Treaty of Angers: Charles the Bald meets Erispoe in Angers, and acknowledges him as "king of Brittany". He recognizes the authority of Breton rule over the areas around Nantes, Rennes and Pays de Retz, which become part of the Breton March, a border zone. Erispoe takes the oath to Charles as king of the West Frankish Kingdom (but not an hommage lige which would be an allegiance). To mark the sovereignty of the Breton state, the future Dukes of Brittany are crowned as "Duke, king in their lands".[7]
Emperor Lothair I meets with his (half) brothers Louis the German and Charles the Bald in Meerssen (modern-day Netherlands), to continue the system of "con-fraternal government".
A Viking fleet of 350 vessels enters the Thames Estuary before turning north, and engages the Mercian forces under King Beorhtwulf. The Mercians are defeated, and retreat to their settlements. The Vikings then turn south and cross the river somewhere in Surrey; there they are slaughtered by a West Saxon army, led by King Æthelwulf and his son Aethelbald, at Oak Field (Aclea).[9]
King Æthelstan, the eldest son of Æthelwulf, is killed by a Viking raiding party. He is succeeded by his brother Æthelberht, who becomes sub-king of Kent, Essex, Surrey and Sussex (approximate date).
Beorhtwulf dies after a 12-year reign, and is succeeded by his son Burgred as king of Mercia.
According to a 17th century account, the Andalusian inventor Abbas ibn Firnas makes a tower jump in Córdoba. He wraps himself with vulture feathers and attaches two wings to his arms. The alleged attempt to fly is not recorded in earlier sources and is ultimately unsuccessful, but the garment slows his fall enough that he only sustains minor injuries.
Danish Vikings attempt to subjugate the Curonians on the shoreline of the Baltic Sea, but they are repulsed. King Olof leads Swedish Vikings in retaliation, and attacks the towns of Seeburg and Apuolė (modern Courland).
Winter – Æthelwulf returns to Wessex to face a revolt by his eldest son Æthelbald, who usurps the throne. Æthelwulf agrees to give up the western part of his kingdom, in order to avoid a civil war. He keeps control over Sussex, Surrey, Essex and Kent, over which Prince Æthelberht has presided.[28]
Viking chieftain Rorik, with the agreement of King Lothair II, leaves Dorestad with a fleet and forces his rival Horik II to recognise him as ruler over Denmark (approximate date).
The first recorded major outbreak of ergotism kills thousands of people in the Rhine Valley. They have eaten bread made from rye infected with the ergot fungus parasite Claviceps purpurea (approximate date).
January 13 – King Æthelwulf of Wessex dies after an 18-year reign, and is succeeded by his eldest son Æthelbald. He marries his father's young widow Judith (daughter of Charles the Bald), and becomes sole ruler of Wessex. His brother, Æthelberht, is left to rule Kent and the south-east of England.
February 13 – King Kenneth I (Cináed mac Ailpín), king of the Scots, dies after a 15-year reign in which he has been crowned at Scone, and united the various parts of Scotland with his native Dál Riata. His 46-year-old brother succeeds as Donald I, king of Alba.
Synod of Quierzy: The bishops remain loyal to Charles the Bald during the invasion of his dominions by Louis the German.[32] They address a conciliatory letter to Louis the German, which includes the False Decretals.