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|Ab urbe condita||2044|
|Balinese saka calendar||1212–1213|
|English Regnal year||19 Edw. 1 – 20 Edw. 1|
|Chinese calendar||庚寅年 (Metal Tiger)|
3987 or 3927
— to —
辛卯年 (Metal Rabbit)
3988 or 3928
|- Vikram Samvat||1347–1348|
|- Shaka Samvat||1212–1213|
|- Kali Yuga||4391–4392|
|Japanese calendar||Shōō 4|
|Minguo calendar||621 before ROC|
|Thai solar calendar||1833–1834|
1417 or 1036 or 264
— to —
1418 or 1037 or 265
|Wikimedia Commons has media related to 1291.|
- Spring – Vandino and Ugolino Vivaldi set sail from Genoa with the goal of reaching India; they never return.
- May 10 – Scottish nobles recognize the authority of King Edward I of England, in mediating the resolution of the succession crisis, created by the death of King Alexander III of Scotland, five years earlier.
- August – The Swiss Confederation is formed by Uri, Schwyz, and Unterwalden (the "three forest cantons"), at Rütli, by the Federal Charter.
- Sancho IV of Castile captures Tarifa from the Moors.
- The Habsburgs acquire the Swiss city of Lucerne.
- Pope Nicholas IV confirms the independence of San Marino, via papal bull.
- All glassmakers in Venice are forced to move to the island of Murano, in order to contain the risk of fire, thus establishing the glass industry there.
- Klenová Castle is constructed in southern Bohemia, as part of a frontier defense system.
- King Andrew III of Hungary gives royal town privileges to Bratislava, the present-day capital of Slovakia.
- Switzerland officially gains its independence.
- May 18 – Al-Ashraf Khalil of Egypt captures Acre, thus exterminating the Crusader Kingdom of Jerusalem (the final Christian landholding remaining from the Crusades), and ending the Ninth Crusade and effectively all Crusades, by eliminating the possibility of further attacks on the Holy Land (see Siege of Acre (1291)).
- The artificial Kunming Lake is constructed as a reservoir for Dadu, Yuan Dynasty, China, by famous engineer and astronomer Guo Shoujing.
- Emperor Kameyama of Japan establishes the Zen Buddhist temple of Nanzenji, in Kyoto.
- Four towns of the county of Holland (Dordrecht, Haarlem, Leiden and Alkmaar) and two of the county of Zeeland (Middelburg and Zierikzee) agree for the first time to collectively secure a loan by their sovereign, Floris V. This system gives important securities to the lenders, and allows the ruler to access the same low interest rates as the cities’ governments.
- Zuijderduijn, Jaco (2010). "The emergence of provincial debt in the county of Holland (thirteenth-sixteenth centuries)". European Review of Economic History. 14 (2).