1251

Europe

 * April - The first, a domestic uprising in response to events in  during the , occurs.
 * - King marries, daughter of King , precipitating a power struggle between the two monarchs.
 * , dispatched two years earlier by King as an ambassador to the s, meets the king in Palestine, with reports from the Mongols and ; his mission is considered a failure.
 * of is baptized, in prelude to his crowning as King of Lithuania in.
 * signs the first peace treaty between and.
 * King invades, but fails to subdue the supporters of.
 * The city of, founded some fifty years earlier, receives its city charter.
 * , later to become King of, is elected.
 * The earliest known manuscript of , a collection of sayings of 's, is written.

Asia

 * is elected as the fourth of the.
 * Carving of the, a collection of  recorded on some 81,000 wooden blocks, is completed.

Births

 * , 8th regent of the (died )

Deaths

 * (born )
 * , commander of
 * (born )
 * (born )