(MCCCXC) was a common year starting on Saturday (link will display full calendar) of the Julian calendar.

• January 19 – The Treaty of Lyck confirms an alliance between Vytautas and the Teutonic Knights, in the Lithuanian Civil War against Vytautas's cousin, Jogaila.
• April 14 – John VII Palaiologos overthrows his grandfather, John V Palaiologos, as Byzantine Emperor.
• April 19 – Robert III succeeds his father, Robert II, as King of Scotland.
• May 26 – Lithuanian Civil War: The Treaty of Königsberg is signed in Königsberg, between Samogitian nobles and representatives of the Teutonic Knights.^[1]
• September 11 – Lithuanian Civil War: The coalition of Vytautas and the Teutonic Knights begins a 5-week siege of Vilnius. The Duke of Hereford (the future King Henry IV of England) is among the western European knights serving with the coalition.^[2]
• September 17 – John VII Palaiologos seeks refuge with the Ottoman sultan Bayezid I, after John V Palaiologos is restored by his son, Manuel, and the Republic of Venice.
• October 9 – Henry III succeeds his father, John I, as King of Castile and León.

• Fall of Philadelphia
  • The Ottomans take Philadelphia, the last Byzantine enclave of any significance in Anatolia.
• Barquq is restored as Mamluk Sultan of Egypt, after overthrowing Sultan Hadji II.
• Nasir ud din Muhammad Shah III overthrows his brother, Abu Bakr Shah, as Sultan of Delhi.
• Manuel III succeeds his father, Alexios III, as Emperor of Trebizond (now north eastern Turkey).
• Sikandar But-shikan succeeds Sikandar Shah, as Sultan of Kashmir.
• Ko Cheng succeeds Che Bong Nga, as King of Champa (now eastern Vietnam).
• Mahmud succeeds Sandaki as Mansa of the Mali Empire, restoring the Keita dynasty.
• N'Diklam Sare succeeds Sare N'Dyaye, as ruler of the Jolof Empire (now part of Senegal).
• The Kingdom of Kaffa is established in present day Ethiopia (approximate date).
• Templo Mayor, the main temple of the Aztec capital of Tenochtitlan (now Mexico City), is built.
• The Candi Surawana Temple is built in the Majapahit Kingdom (now Indonesia).
• Construction begins on San Petronio Basilica in Bologna.

• October 3 – Humphrey, Duke of Gloucester (d. 1447)
• December 27 – Anne de Mortimer, claimant to the English throne (d. 1411)
• date unknown
  • Moctezuma I, Aztec ruler of Tenochtitlan, son of Huitzilihuitl (d. 1469)^[3]
• probable
  • John Dunstaple, English composer (d. 1453)
  • Engelbrekt Engelbrektsson, Swedish statesman and rebel leader (d. 1436)
  • Contessina de' Bardi, politically active Florentine woman (d. 1473)
  • Jan van Eyck, Flemish painter (d. 1441)

• January 26 – Adolph IX, Count of Holstein-Kiel (b.c 1327)
• February 16 – Rupert I, Elector Palatine (b. 1309)
• March 20 – Alexios III Megas Komnenos, Emperor of Trebizond (b. 1338)
• April 19 – King Robert II of Scotland (b. 1316)
• July 8 – Albert of Saxony, Bishop of Halberstadt and German philosopher (b. c. 1320)
• August 14 – John FitzAlan, 2nd Baron Arundel, English soldier (b. 1364)
• September 23 – John I, Duke of Lorraine (b. 1346)
• October 9 – King John I of Castile (fall from a horse) (b. 1358)
• September – Towtiwil, Prince of Black Ruthenia
• date unknown
  • Sandaki Mari Djata, Mansa of the Mali Empire
  • Keratsa of Bulgaria, Byzantine empress consort
  • Sa'ad al-Din Masud ibn Umar ibn Abd Allah al-Taftazani, Ilkhanate polymath (b. 1322)
• probable – Altichiero, Italian painter (b. 1330)