|Covid-19|The Aragonese navy raids the Tunisian Kerkennah Islands.
April 4 – Wareru creates the Hanthawaddy Kingdom in modern-day Lower Burma.
c. May 14–July 16 – Kublai Khan personally leads a large force to suppress the rebel prince Nayan in Manchuria.
December – Battle of Pagan: The Theravada Buddhist Pagan Kingdom (in modern-day Myanmar) falls to the invading armies of the Yuan dynasty.
Kings Mangrai of the Lanna kingdom and Ram Khamhaeng of the Sukhothai Kingdom agree to a peace pact in their region of southeast Asia (modern-day Thailand).
Mongol Ilkhan Arghun dispatches Rabban Bar Sauma to the leaders of Europe to negotiate an alliance against the Muslim states, specifically the Mamluk sultanate of Egypt.
Mamluk sultan Al Mansur Qalawun captures the port city of Latakia in present-day Syria.
January 17 – The Treaty of San Agayz is signed. King Alfonso III of Aragon conquers the island of Minorca from the Moors.
February – South England flood, affecting the Cinque Ports of England: A storm surge destroys the town of Old Winchelsea on Romney Marsh and nearby Broomhill. The course of the nearby River Rother is diverted away from New Romney, which is almost destroyed, ending its role as a port, with the Rother running instead to the sea at Rye, whose prospects as a port are enhanced. A cliff collapses at Hastings, ending its role as a trade harbour and demolishing part of Hastings Castle. New Winchelsea is established on higher ground.
June 8 – Rhys ap Maredudd revolts in Wales; the revolt will not be suppressed until 1288.
December 14 – A huge storm and associated storm tide in the North Sea and English Channel, known as St. Lucia's flood in the Netherlands, kills thousands and reshapes the coastline of the Netherlands and England.
In the Netherlands, a fringing barrier between the North Sea and a shallow lake collapses, causing the fifth largest flood in recorded history which creates the Zuider Zee inlet and kills over 50,000 people; it also gives sea access to Amsterdam, allowing its development as an important port city.
In England, parts of Norfolk are flooded; the port of Dunwich in Suffolk is further devastated; and in The Fens through the vehemence of the wind and the violence of the sea, the monastery of Spalding and many churches are overthrown and destroyed "All the whole country in the parts of Holland was for the most part turned into a standing pool so that an intolerable multitude of men, women and children were overwhelmed with the water, especially in the town of Boston, a great part thereof was destroyed."
King Edward I of England orders the expulsion of Jews from the duchy of Gascony and confiscates their property.
The Mongol Golden Horde, led by khan Talabuga and Nogai Khan, attacks Poland for the third time. Lublin, Mazovia, Sandomierz and Sieradz are ravaged by the invaders, who are defeated in Kraków.
In Aragon, the Uniones, an aristocratic uprising, forces Alfonso III to make concessions to the nobility. In particular, the king grants his barons a bill of rights, known as the Privilegium Generale.
The Bruntál coat of arms makes its first appearance.
The Altar of St. James in Pistoia Cathedral, Italy – a masterwork of the silversmithing trade containing nearly a ton of silver – is begun; it will not be completed for nearly 200 years.
The Italian city of Siena exacts a forced loan on its taxpayers for the first time, a common feature of medieval public finance.
Construction on Uppsala Cathedral in Sweden begins and last until 1435.
January 24 – Richard Aungerville, English writer and bishop (d. 1345)
April 25 – Roger Mortimer, 1st Earl of March, de facto ruler of England (d. 1330)
Robert III of Artois
Wang Mian, Chinese painter (d. 1359)
April 3 – Pope Honorius IV
August 31 – Konrad von Würzburg, German poet
October 19 – Bohemond VII, Count of Tripoli
Llywelyn ap Dafydd, a Welsh prince (in his prison at Bristol Castle)
Year 1287 (MCCLXXXVII) was a common year starting on Wednesday (link will display the full calendar) of the Julian calendar.