1400

Year 1400 (MCD) was a leap year starting on Thursday of the Julian calendar. The year 1400 wasn't a leap year in the Proleptic Gregorian calendar.
Events
January-December
January - Henry IV of England stops the Epiphany Rising and kills the Earls of Kent, Huntingdon and Salisbury and the Baron le Despencer, because they tried to have Richard II made as king.
February - Henry Percy (Hotspur) leads English army into Scotland.
February 14 - Richard II of England dies in Pontefract Castle but we don't know what killed him. King Henry IV might have ordered people to starve him to death.
March 23 - Five-year-old Tran Thieu De is forced to stop being the ruler of Dai Viet (modern-day Vietnam) and give the throne to his maternal grandfather Ho Quy Ly. This was the end of the Tran Dynasty after 175 years and the start of the Ho Dynasty. Ho Quy Ly changes the country's name to Dai Ngu.
May - Frederick I, Duke of Brunswick-Luneburg tries to take over from Wenceslaus, King of the Romans. However, Frederick is murdered shortly after.
August
The English capture the city of Edinburgh in Scotland but do not capture Edinburgh Castle.
The princes of the German states vote that Wenceslaus is not King of the Romans because he did a bad job as king and because of his mental illnesses.
August 21 - Rupert, Count Palatine of the Rhine, is elected as King of the Romans.
September 16 - Owain Glyndwr is made Prince of Wales by the Welsh, and he starts attacking English castles in north-east Wales.
November - Sack of Aleppo (1400) during Timur's conquest of Syria.
December - Manuel II Palaiologos becomes the only Byzantine Emperor ever to visit England.
Date unknown
Timur wins against the Ottoman Empire and the Mamluk Sultanate of Egypt. Timur captures the city of Damascus what is today Syria. Timur's army kills many of the city's people.
Timur conquers the Empire of the Black Sheep Turkomans, in present-day Azerbaijan, and the Jalayirid Dynasty in present-day Iraq. Black Sheep ruler Qara Yusuf and Jalayirid Sultan Ahmad run away and go to live with the Ottoman Sultan Bayezid I.
King Jeongjong of Joseon stops being king because he is afraid his younger brother, Taejong, will attack him. Taejong becomes king.
Prince Parameswara starts the Malacca Sultanate, in what is western Malaysia and northern Sumatra today.
Hananchi succeeds Min as King of Hokuzan in what is Okinawa, Japan today.
Wallachia (modern-day southern Romania) stops the Ottomans from invading.
A Wallachian army captures Iuga, and makes Alexandru cel Bun the Prince of Moldavia.
The Kingdom of Kongo begins.
The Haast's eagle and Moa are both made extinct by Maori hunters.
The Mississippian culture starts to decline.
Europe is reported to have around 52 million inhabitants.
The House of Medici becomes powerful in Florence.
Newcastle upon Tyne is created a county corporate by Henry IV of England.
Jean Froissart completes his Chronicles, detailing the events of the 14th Century in France.
Births
January 13 - Infante John of Portugal, the Constable (d. 1442)
May 19 - John Stourton, 1st Baron Stourton, English baron (d. 1462)
July 26 - Isabel le Despenser, Countess of Worcester, English noble (d. 1439)
December 25 - John Sutton, 1st Baron Dudley, Lord Lieutenant of Ireland (d. 1487)
date unknown
James Tuchet, 5th Baron Audley (d. 1459)
Luca della Robbia, Florentine sculptor (d. 1482)
Isabella, Duchess of Lorraine (d. 1453).