|Covid-19|July 2 – Kings Otakar II of Bohemia and Stephen V of Hungary sign the first Peace of Pressburg, settling territorial claims following the failed invasion of Hungary by Otakar II.
September 1 – Pope Gregory X succeeds Pope Clement IV as the 184th pope, as the compromise candidate between French and Italian cardinals, ending a 3-year conclave, the longest ever.
The County of Toulouse is returned to the crown of France.
Marco Polo departs from Venice with his father and uncle on his famous journey to Kublai Khan's China.
The construction of Caerphilly Castle, the largest in Wales, is completed.
Construction of the Belaya Vezha in Belarus is begun.
April 8 – Mamluk sultan Baibars continues his territorial expansion, capturing the strategically important castle Krak des Chevaliers from the Knights Hospitaller in present-day Syria.
Mamluk sultan Baibars conducts an unsuccessful siege of the city of Tripoli, and also fails in an attempted naval invasion of Cyprus.
Edward I of England and Charles of Anjou arrive in Acre, starting the Ninth Crusade against Baibars; however, they are unable to capture any territory and a peace is quickly negotiated.
September 12 – Nichiren was nearly beheaded. This incident, known as Hosshaku Kempon or "casting off the transient and revealing the true,", is regarded as a turning point of Nichiren’s teachings within the various schools known as Nichiren Buddhism.
December 18 – Kublai Khan renames his empire "Yuan" (元 yuán), officially marking the start of the Yuan Dynasty of China.
The Nakhi kingdom of the northern Himalayan foothills is annexed by the Yuan Dynasty.
September 8 – Charles Martel of Anjou, son of Charles II of Naples (d. 1295)
September 27 – King Wenceslaus II of Bohemia and Poland (d. 1305)
November 5 – Mahmud Ghazan, Mongol ruler (d. 1304)
Emperor Bing of Song (d. 1279)
Elizabeth of Aragon, queen of Denis of Portugal (d. 1336)
Mikhail Yaroslavich, Grand Prince of Vladimir (d. 1318)
Duke Rudolph II of Austria (d. 1290)
January 18 – Saint Margaret of Hungary (b. 1242)
January 28 – Isabella of Aragon, queen of Philip III of France (b. 1247)
March 13 – Henry of Almain, English crusader (b. 1235)
July 28 – Walter de Burgh, 1st Earl of Ulster (b. 1220)
August 21 – Alphonse, Count of Poitiers, son of Louis VIII of France (b. 1220)
August 25 – Joan, Countess of Toulouse (b. 1271)
September 9 – Yaroslav of Tver, Grand Duke of Vladimir
October 17 – Steinvör Sighvatsdóttir, Icelandic aristocrat and poet
Haji Bektash Veli, Khorasanian mystic (b. 1209)
Richard de Grey, Lord Warden of the Cinque Ports
Baraq, khan of the Chagatai Khanate
Year 1271 (MCCLXXI) was a common year starting on Thursday (link will display the full calendar) of the Julian calendar.