Year 1100 (MC) was a century leap year starting on Sunday (link will display the full calendar) of the Julian calendar. In the proleptic Gregorian calendar, it was a non-leap century year starting on Monday (like 1900).
|Ab urbe condita||1853|
|Balinese saka calendar||1021–1022|
|English Regnal year||13 Will. 2 – 1 Hen. 1|
|Chinese calendar||己卯年 (Earth Rabbit)|
3796 or 3736
— to —
庚辰年 (Metal Dragon)
3797 or 3737
|- Vikram Samvat||1156–1157|
|- Shaka Samvat||1021–1022|
|- Kali Yuga||4200–4201|
|Japanese calendar||Kōwa 2|
|Minguo calendar||812 before ROC|
|Seleucid era||1411/1412 AG|
|Thai solar calendar||1642–1643|
1226 or 845 or 73
— to —
1227 or 846 or 74
|Wikimedia Commons has media related to 1100.|
- The Ancestral Puebloan culture rises (approximate date).
- Oraibi becomes and remains the first and oldest populated settlement in what today is the United States and what is now Arizona.
- The city of Cusco, Peru is founded.
- The Liao Dynasty crushes the Zubu, and takes their khan prisoner.
- Song Dynasty China's population reaches roughly 100 million.
- In the Song Dynasty capital of Kaifeng, the number of registered people within the walls is 1,050,000; the army stationed there boosts the overall populace to some 1.4 million people.
- Emperor Huizong of Song starts to rule in China.
- January – The Saljukid ruler Mahmud I is expelled from Bagdad by his brother Barkiyaruq, but Mahmud I manages to retake the city, during his spring offensive.
- May or June – Raymond de Saint-Gilles sails to Byzantium to obtain the support of the emperor Alexios, in his attempt to seize Tripoli.
- August 1 – A Genoese fleets leaves Italy, to support the Crusaders' effort to conquer the coastal cities; the ships reach Latakia on September 25.
- August – Battle of Melitene: Bohemond I of Antioch is captured by the Danishmends, leaving Tancred as regent of the Principality of Antioch for two years.
- August 20 – With the support of the Venetian fleet, the Crusaders under Tancred of Hauteville capture the coastal city of Haifa.
- December 25 – Baldwin I is crowned first King of Jerusalem at the Church of the Nativity in Bethlehem, by Dagobert of Pisa, the new Latin Patriarch of Jerusalem, following the death of the previous ruler, Baldwin's brother Godfrey of Bouillon, on July 18.
- After a success over the Armenians of Cilicia and the Emirate of Aleppo, Baldwin of Bourcq becomes Count of Edessa, with the support of the patriarch Dagobert of Pisa.
- Genoa, Venice and Pisa gain trading privileges from the Crusader states, in return for their service during the conquest of the coastal cities.
- August 2 – King William II (or William Rufus) dies in a hunting accident in the New Forest; his brother Henry I claims the throne.
- August 5 – Henry I is crowned King of England, at Westminster Abbey. The power of the new monarch is ill-assured, and to mollify the barons he has to grant them the Charter of Liberties, one of the first examples of a written constitution in Europe.
- August 30 – After the failure of the Council of Liubech in 1097, the Congress of Vytechev establishes peace and the feudal system in Kievan Rus; the princes come to an agreement to share the country between them, and Sviatopolk II of Kiev becomes the first Grand Prince.
- September 16 – Battle of Malagon: The Almoravid army defeats Castellan troops.
- September 23 – Archbishop of Canterbury Anselm returns from exile, at the invitation of Henry I of England.
- October 18 – Peter I of Aragon conquers Barbastro (North) from the hands of the Almoravids.
- November 11 - Henry I marries Matilda of Scotland, the daughter of King Malcolm III and a direct descendant of the Saxon king Edmund Ironside.
- November 18 – The Council of Poitier opens, but is soon forcibly closed by the duke of Aquitaine, William IX, as the bishops were about to excommunicate once more the king of France, Philip I.
- December 25 – Philip I elevates his son Louis VI to the government of the realm.
- In Iceland, the Althing decides that the laws should be transferred to a written form.
- Intense urban activity in north and central Europe: Kalmar (Kungälv) and Varberg (Sweden) are chartered; The cities of Aach (southern Germany) and Nakléřov (in Bohemia (German: Nollendorf) are created, and the castle of Burgg Eppstein is built in central Germany.
- Philip I of France conquers the Vexin area, and adds the city of Bourges and the province of Berry to his estate.
- Dagobert of Pisa becomes Latin Patriarch of Jerusalem.
- At the death of Antipope Clement III, supporters of the Holy Roman Emperor in Rome choose Theodoric as his successor.
- Frederick I of Schwarzburg becomes archbishop of Cologne, and begins the construction of the castle of Volmarstein.
- The Stift St. Georgen Abbey is founded near Sankt Georgen am Längsee (Austria).
- The Diocese of Faroe is founded (approximate date).
- May 23 – Qin Zong, Chinese emperor (d. 1161)
- Adrian IV, pope of the Catholic Church (d. 1159)
- Alexander III, pope of the Catholic Church (d. 1181)
- Eliza and Mary Chulkhurst, English conjoined twins (d. 1134)
- Gilbert de Clare, 1st Earl of Pembroke (d. 1148)
- Héloïse d'Argenteuil, French abbess and scholar (d. 1162)
- Robert de Beaumont, 2nd Earl Leicester (d. 1168)
- Robert de Ferrers, 2nd Earl of Derby (d. 1162)
- February 23 – Zhe Zong, Chinese emperor (b. 1077)
- March 28 – Adelaide of Weimar-Orlamünde, German noblewoman
- June 20 – William I, French nobleman
- July 18 – Godfrey of Bouillon, French nobleman (b. 1060)
- July 23 – Warner of Grez, French nobleman
- August 2 – William II (or William Rufus), king of England
- September 8 – Clement III, antipope of Rome
- September 16 – Bernold of Constance, German chronicler
- October 13 – Guy I (or Wido), French nobleman
- November 18 – Thomas of Bayeux, archbishop of York
- December 22 – Bretislav II, duke of Bohemia
- Abu al-Yusr al-Bazdawi, Hanafi-Maturidi scholar (b. 1030)
- Azzo of Gobatsburg, Swedish nobleman (approximate date)
- Ermengarde of Nevers, French noblewoman (b. 1073)
- Jaya Pala, Indian ruler of the Kamarupa Kingdom (b. 1075)
- Robert de Stafford, Norman nobleman (approximate date)
- Maalouf, Amid (1983). La Croisade vue par les Arabes. Paris: Lattès. p. 74. ISBN 978-2-7096-0547-2.
- Hill, John Hugh; Hill, Laurita Lyttleton (1959). Raymond IV de Saint-Gilles, 1041 (ou 1042)-1105. Privat.
- Hagenmeyer, Hendrich (1973). Chronologie de la première croisade, 1094-1100. Olms. ISBN 978-3-487-04756-0.
- "Baldwin I of Edessa". Retrieved 5 August 2010.
- "Communal Courts". Archived from the original on 23 June 2010. Retrieved 5 August 2010.
- Buresi, Pascal (2004). La frontière entre chrétienté et islam dans la péninsule Ibérique. Publibook. ISBN 978-2-7483-0644-6.
- Sénac, Philippe (2000). La frontière et les hommes, VIIIe-XIIe siècle. Maisonneuve et Larose. ISBN 978-2-7068-1421-1.
- Catlos, Brian A. (2004). The victors and the vanquished: Christians and Muslims of Catalonia and Aragon, 1050-1300. Cambridge: Cambridge University Press. p. 13. ISBN 0-521-82234-3.
- O'Reilly, Patrice-John (1857). Histoire complète de Bordeaux, Volume 1, Parties 1 à 2. Delmas.
- Hoefer, Jean (1862). Nouvelle biographie générale. Firmin Didot frères.
- "The history of checkers". Archived from the original on February 22, 2010. Retrieved August 5, 2010.