920

By place

Byzantine Empire

• December 17 - Romanos I has himself crowned co-emperor of the Byzantine Empire. He shares the throne with the 15-year-old Constantine VII, and constructs an alternative palace at Constantinople with an adjoining monastery near the Great Palace. Though Constantine retains his formal position as first on the protocol list, Romanos becomes sole ruler.

  Europe

• The nobles of Lotharingia under Gilbert, duke of Lorraine, revolt against King Charles III. They recognize King Henry I as their sovereign. Charles invades Lotharingia as far as Pfeddersheim, but retreats when he learns that Henry is mobilizing an army to attack the West Frankish Kingdom.
• Henry I conquers Utrecht, which has been in possession of the Vikings for 70 years. Balderic, bishop of Utrecht, moves his seat back from Deventer to Utrecht.

  Britain

• High-Reeve Ealdred I, ruler of the former kingdom of Bernicia, and his brother Uhtred, submit to the overlordship of King Edward the Elder.
• The Welsh ruler Hywel Dda merges Dyfed and Seisyllwg, establishing a new kingdom known as Deheubarth.

  Iberian Peninsula

• July 26 — At the Battle of Valdejunquera, the Muslim forces of the Emir Abd-ar-Rahman III of Córdoba, defeat the Christian armies of King Ordoño II of León and King Sancho I of Pamplona. The decisive battle at the Val de Junquera takes place following the Emir's pre-emptive strike and his invasion of the upper Douro valley and the capture of Osma. The Arab army proceeds on to the upper Ebro, restoring and replenishing Umayyad garrisons in the region.

  Africa

• The Golden Age of the Ghana Empire begins in Africa.

  Asia

• Emperor Taizu of the Khitan Empire orders the adoption of a written script by the Khitan, resulting in the creation of Khitan "Large Script."

  By topic

Climate

• Muslim chroniclers in Baghdad record an unusually cold summer.