1121

By place

Byzantine Empire

• Emperor John II recovers southwestern Anatolia from the Seljuk Turks, and then hastens to the Balkans, where the Pechenegs are continuing their incursions. He transfers Byzantine troops to the Danube frontier at Paristrion.

  Levant

• Summer - Seljuk forces under Toghtekin make extensive raids into Galilee. King Baldwin II, in reprisal, crosses the Jordan River with a Crusader army, and ravages the countryside. He occupies and destroys a fortress that Toghtekin has built at Jerash.

  Europe

• March 2 - Petronilla of Lorraine becomes regent of Holland after her husband, Floris II dies. He is succeeded by his 6-year-old son Dirk VI.
• A large rebellion takes place in Córdoba against the ruling Almoravid Dynasty.

  England

• January 24 - Adeliza of Louvain, age 17, marries King Henry I two months after the accidental death of the heir to the English throne, Henry's only legitimate son, William Adelin.

  Eurasia

• Summer - Sultan Mahmud II of the Seljuk Empire declares a Holy War on Georgia. He sends an expedition under Ilghazi ibn Arttuq, Artukid ruler of Mardin, to invade Georgia.
• August 12 - Battle of Didgori: King David IV of Georgia, with a Georgian army, defeats the 300,000-strong Seljuk coalition forces at Mount Didgori.

  Asia

• Emperor Hui Zong sends an expedition to crush the rebellion at Hangzhou in China. The rebels are defeated, their leader Fang La is captured and executed.

  By topic

Religion

• Spring - Peter Abelard, a French theologian and philosopher, is condemned and charged with the heresy of Sabellius in a synod at Soissons. Abelard writes Sic et Non.
• April 22 - Antipope Gregory VIII is arrested by papal troops at Sutri. He is taken to Rome and imprisoned in the Septizonium.
• December 25 - The Praemonstratensian Order is formed, when a group of canons make solemn vows at Prémontré.
• Henry I founds Reading Abbey in England. The Cluniac Order populates the abbey.
• The third and largest church is completed at Cluny Abbey.
• L'Aumône Abbey is founded by Count Theobald IV of Blois at Loir-et-Cher.