1256

Events 
 Europe 
 May 4 – Pope Alexander IV issues a papal bull Licet ecclesiae catholicae constituting the Augustinian monastic order at Lecceto Monastery.
 The city of Lviv, in present-day Ukraine, is founded by Danylo King of Rus.
 Theodore II Lascaris, Byzantine Emperor (in exile in the Empire of Nicaea), successfully concludes a military campaign started a year earlier to recover Thrace from the Bulgarians.
Abingdon School is founded.
Roger Bacon becomes a Franciscan Friar.

 Asia 
 October – Mongol commander Baiju (operating under Hulagu Khan's command) leads his forces in a victory over Kay Ka'us II of the Sultanate of Rüm, thereby capturing Anatolia.
 December 15 – Hulagu Khan captures and destroys the Hashshashin stronghold at Alamut in present-day Iran.
 Hulagu Khan establishes the Ilkhanate dynasty of Persia, which will become one of four main divisions of the Mongol Empire.
 The Japanese Kenchō era ends, and the Kōgen era begins.

 Births 
 January 6 – Gertrude the Great, German mystic
 Robert, Count of Clermont, French founder of the House of Bourbon (died 1317)

 Ibn al-Banna, Arab Mathematician (died 1321)

 Deaths 
 January 28 – William II, Count of Holland, King of Germany
 June 13 – Tankei, Japanese sculptor (born 1173)
 September 1 – Kujo Yoritsune, Japanese shogun (born 1218)
 October 14 – Kujo Yoritsugu, Japanese shogun (born 1239)
 William of Kilkenny, Lord Chancellor of England
 Johannes de Sacrobosco, English scholar