1238

Events 
 Battle of the Sit River was fought in the northern part of the present-day Yaroslavl Oblast of Russia between the Mongol Hordes of Batu Khan and the Russians under Yuri II of Vladimir during the Mongol invasion of Russia.
 In the Iberian peninsula, James I of Aragon captures the city of Valencia September 28 from the Moors; the Moors retreat to Granada.
 Mongols seize Moscow, at that time a small town.
 Peterborough Cathedral is consecrated.
 The Khmers are expelled from Luang Phrabang in Laos.
 The Sukhothai kingdom is founded in Thailand.
 The seat of the patriarchate of Aquileia is transferred to Udine.
 Simon de Montfort marries Eleanor, sister of Henry III of England.
 The Battle of Örlygsstaðir takes place – it is the largest armed conflict in the history of Iceland