|Ab urbe condita||1876|
|Balinese saka calendar||1044–1045|
|English Regnal year||23 Hen. 1 – 24 Hen. 1|
|Chinese calendar||壬寅年 (Water Tiger)|
3819 or 3759
— to —
癸卯年 (Water Rabbit)
3820 or 3760
|- Vikram Samvat||1179–1180|
|- Shaka Samvat||1044–1045|
|- Kali Yuga||4223–4224|
|Japanese calendar||Hōan 4|
|Minguo calendar||789 before ROC|
|Seleucid era||1434/1435 AG|
|Thai solar calendar||1665–1666|
1249 or 868 or 96
— to —
1250 or 869 or 97
|Wikimedia Commons has media related to 1123.|
- August 9 – Battle of al-Dimas: A Norman campaign in North Africa ends with their troops being massacred near Mahdia.
- February 25 – 5-year-old Emperor Sutoku succeeds his father Emperor Toba on the throne of Japan, when the latter is forced to abdicate at the age of 21.
- May 29 – Battle of Yibneh: A Crusader force led by Eustace Grenier crushes a Fatimid army at Yibna.
- May 30 – The Venetian fleet defeats the Egyptian fleet off Ascalon.
- The Pactum Warmundi is established between the Republic of Venice and the Kingdom of Jerusalem.
- May 9 – A fire in the English city of Lincoln nearly destroys the Lincolnshire town; it is memorialized 600 years later by historian Paul de Rapin 
- The consuls of Bologna are first mentioned, indicating that the city has become an independent commune of Italy.
- Siege of Deventer: Conflict between Henry V, Holy Roman Emperor and Lothair of Supplinburg, Duke of Saxony.
- In accordance with the decision of the First Council of the Lateran, the archbishop of Compostela, Diego Gelmírez, declares the Crusade in Iberia against the Andalusians.
- King Sigurd the Crusader of Norway performs a crusade, the Kalmare ledung, against the Swedish province of Småland.
- March 18 – First Council of the Lateran convenes in Rome; it confirms the Concordat of Worms (1122) and demands clerical celibacy in the Catholic Church.
- The Priory church of St Bartholomew-the-Great and St Bartholomew's Hospital ("Barts") are founded in London by Rahere. The Priory church is now a Church of England parish church. The hospital is still operating as a medical institution on its original site.
- Furness Abbey is founded in the north-west of England by Stephen, Count of Boulogne, for the Order of Savigny; it will become the country's second wealthiest and most powerful Cistercian monastery.
- Meynier, Gilbert (2010). L'Algérie cœur du Maghreb classique: De l'ouverture islamo-arabe au repli (658-1518). Paris: La Découverte. p. 56.
- Johns, Jeremy (2002). Arabic administration in Norman Sicily: the royal dīwān. Cambridge University Press. p. 85. ISBN 0-521-81692-0.
- "Venice - Adriatic Powerhouse". Pericles Press. 2013. Retrieved February 3, 2014.
- "Fires, Great", in The Insurance Cyclopeadia: Being an Historical Treasury of Events and Circumstances Connected with the Origin and Progress of Insurance, Cornelius Walford, ed. (C. and E. Layton, 1876) pp72
- Fletcher, R. A. (1987). "Reconquest and Crusade in Spain c. 1050-1150". Transactions of the Royal Historical Society. 5. 37: 31–47 . JSTOR 3679149.