|Ab urbe condita||2030|
|Balinese saka calendar||1198–1199|
|English Regnal year||5 Edw. 1 – 6 Edw. 1|
|Chinese calendar||丙子年 (Fire Rat)|
3973 or 3913
— to —
丁丑年 (Fire Ox)
3974 or 3914
|- Vikram Samvat||1333–1334|
|- Shaka Samvat||1198–1199|
|- Kali Yuga||4377–4378|
|Japanese calendar||Kenji 3|
|Minguo calendar||635 before ROC|
|Thai solar calendar||1819–1820|
1403 or 1022 or 250
— to —
1404 or 1023 or 251
|Wikimedia Commons has media related to 1277.|
- March 7 – Condemnation of 1270: 219 philosophical and theological doctrines such as Averroism are prohibited from discussion in the University of Paris, under a decree promulgated by Étienne Tempier, Bishop of Paris.
- March 18 – Charles of Anjou buys the title to the Kingdom of Jerusalem from Mary of Antioch, for 1,000 bezants and an annual payment of 4,000 livres tournois.
- April 15 – Battle of Elbistan: Mamluk sultan Baibars invades the Seljuk Sultanate of Rûm, and defeats a Mongol army.
- November 25 – Pope Nicholas III succeeds Pope John XXI, as the 188th pope.
- Battle of Ngasaunggyan: Burma's Pagan Empire begins to disintegrate, after being defeated by Kublai Khan at Yunnan, near the Chinese border.
- Some 50,000 leaders and citizens of the Southern Song Dynasty of China become the first recorded inhabitants of Macau, as they seek refuge from the invading armies of the Yuan Dynasty. They also stay for a short period in Kowloon. Some hundred years later, the place where they stayed becomes Sung Wong Toi.
- The Treaty of Aberconwy is signed by Llywelyn ap Gruffudd, Prince of Wales, and King Edward I of England, ending the First Welsh War, in exchange for restrictions on Llywelyn's power.
- St George's Cross is first recorded in use, as the national flag of England.
- In Japan, a 20 kilometer stone wall defending the coast of Hakata Bay in Fukuoka is completed; it is built in response to the attempted invasion by the Yuan Dynasty in 1274.
- In England, Roger Bacon, a Franciscan friar and University of Oxford lecturer, was arrested for spreading anti-Church views; specifically the Church's stance on the Greek philosopher Galen.
- Sempad of Armenia, king of the Armenian Kingdom of Cilicia (d. c. 1310)
- Isabella of Mar, Scottish countess, first wife of Robert Bruce (approximate date; d. 1296)
- Martha of Denmark, queen consort of Sweden (d. 1341)
- January–March – Philip of Sicily, titular King of Thessalonica
- May 1 – Stefan Uroš I of Serbia
- May 20 – Pope John XXI (b. 1215)
- July 1 – Baibars, Mameluk sultan of Egypt (b. 1223)
- August 2 – Mu'in al-Din Sulaiman Pervane, Chancellor and Regent of the Sultanate of Rum
- October 17 – Beatrice of Falkenburg, German queen consort (b. c. 1254)
- October 27 – Walter de Merton, Lord Chancellor of England and founder of Merton College, Oxford
- date unknown