|1238 by topic|
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- March 4 – Mongol invasion of Rus – Battle of the Sit River: The Mongol Hordes of Batu Khan defeat the Rus', under Yuri Vsevolodovich of Vladimir-Suzdal.
- August 21 – Battle of Örlygsstaðir: Sighvatr Sturluson and Sturla Sighvatsson are defeated by Kolbeinn ungi Arnórsson and Gissur Þorvaldsson, for control of Iceland.
- September 28 – James I of Aragon captures the city of Valencia from the Moors, who retreat to Granada.
- The seat of the Patriarch of Aquileia is transferred to Udine.
- Simon de Montfort marries Eleanor, sister of Henry III of England.
- The Livonian Order gives Northern Estonia back to Denmark, with the Treaty of Stensby.
- The Mongols seize Moscow, at the time a small town.
- Peterborough Cathedral is consecrated.
- The founder of the Nasrid Dynasty, Mohammed I ibn Nasr, begins Alhambra Complex on the site of a pre-Islamic fortress.
- Thowadra Monastery is founded in Bhutan.
- May 1 – Magnus Lagabøte, king of Norway (d. 1280)
- May 3 – Emilia Bicchieri, Italian saint (d. 1314)
- November – Henry de Montfort, son of Simon de Montfort, 6th Earl of Leicester (d. 1265)
- date unknown
- March 4
- March 19 – Henry I the Bearded, Duke of Lower Silesia (b. c. 1165)
- June 9 – Peter des Roches, bishop of Winchester
- date unknown