For broader historical context, see 13th century.

Events

Europe

• April 13 - Pope Alexander IV issues a papal bull constituting the Augustinian monastic order.
• 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.

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 Kencho era ends, and the Kogen era begins.

Births

• Robert, Count of Clermont, founder of the House of Bourbon
• Saint Gertrude

Deaths

• January 28 - William II, Count of Holland and King of Germany
• September 1 - Kujo Yoritsune, fourth shogun of the Kamakura shogunate in Japan
• October 14 - Kujo Yoritsugu, fifth shogun of the Kamakura shogunate in Japan
• William of Kilkenny, Lord Chancellor of England
• Johannes de Sacrobosco, English scholar

See also

List of state leaders in 1256