1120

By place

Byzantine Empire

• Siege of Sozopolis: Byzantine forces under Emperor John II conquer Sozopolis in Pisidia, from the Sultanate of Rum. The Seljuk garrison is defeated while they are trapped between the Byzantine cavalry and the army.

  Levant

• January 16 - Council of Nablus: King Baldwin II and Patriarch Warmund convenes a assembly at Nablus – establishing the earliest surviving written laws of the Crusader Kingdom of Jerusalem. The prelates and noblemen who attend the meeting confirm the clergy's right to collect the tithe and to bear arms "in the cause of defense".
• Baldwin II grants the Knights Templar under Hugues de Payens and Godfrey de Saint-Omer a headquarters in a wing of the royal palace on the Temple Mount in the captured Al-Aqsa Mosque in the Old City of Jerusalem.
• Summer - Baldwin II leads a expedition to Antioch to defend the northern Crusader states. He signs a 1-year truce with Ilghazi, Artuqid ruler of Mardin, securing the possession of Kafartab and other fortresses in Syria.

  Europe

• June 17 - Battle of Cutanda: The combined forces of Aragon and Navarre under King Alfonso I crush the Almoravid army near Calamocha. Alfonso recaptures the fortified towns of Calatayud and Daroca.
• The Almoravid fleet under Amirals Abu Abd Allah ibn Maymum of Almeria, and Isa ibn Maymum of Sevilla attacks the coastline of the Christian Kingdom of Galicia.
• Freiburg is founded by Conrad I and his elder brother, Duke Berthold III of Zähringen, as a free market town.

  England

• King Henry I gives a portion of the Stoneleigh estate to Geoffrey de Clinton, his chamberlain and treasurer. He builds a motte and bailey castle and forms a lake to provide better defences.
• November 25 - The White Ship is sunk in the English Channel, off Barfleur. Henry I's only legitimate son, William Adelin, is among 300 who drown.
• The Pseudo-Ingulf's Croyland Chronicle records Cornwall, as a nation distinct from England.

  Asia

• Fang La, a Chinese rebel leader, leads an uprising against the Song Dynasty in Qixian Village in southeast China. He raises an army and captures Hangzhou.
• August - September - Wanyan Xiyin, a Jurchen nobleman and minister, completes the design of the first version of the Jurchen script.
• The flourishing south Chinese coastal city of Quanzhou claims a population of 500,000 citizens, including the hinterland.

  By topic

Astronomy

• Walcher of Malvern, an English astronomer and mathematician, creates a system of measurement for the Earth using degrees, minutes and seconds of latitude and longitude.

  Religion

• Bishop Urban begins the construction on Llandaff Cathedral in Wales.