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|Ab urbe condita||2156|
|Balinese saka calendar||1324–1325|
|English Regnal year||4 Hen. 4 – 5 Hen. 4|
|Chinese calendar||壬午年 (Water Horse)|
4099 or 4039
— to —
癸未年 (Water Goat)
4100 or 4040
|- Vikram Samvat||1459–1460|
|- Shaka Samvat||1324–1325|
|- Kali Yuga||4503–4504|
|Japanese calendar||Ōei 10|
|Minguo calendar||509 before ROC|
|Thai solar calendar||1945–1946|
1529 or 1148 or 376
— to —
1530 or 1149 or 377
|Wikimedia Commons has media related to 1403.|
- January/February – In the Treaty of Gallipoli, Süleyman Çelebi makes wide-ranging concessions to the Byzantine Empire and other Christian powers in the southern Balkans.
- February 7 – King Henry IV of England marries as his second wife Joan of Navarre, the daughter of King Charles II of Navarre and widow of John IV, Duke of Brittany, at Winchester Cathedral.
- March 12 – As King Martin I of Aragon helps to end the siege by the French of the papal palace in Avignon, Antipope Benedict XIII flees to Aragon.
- April – Balša III succeeds his father Đurađ II as ruler of the Principality of Zeta (now the Republic of Montenegro).
- May 21 – Ruy Gonzalez de Clavijo, an ambassador from the king of Castile to Timur, leaves Cadiz; he arrives in Samarkand over a year later.
- Before July 21 – Henry 'Hotspur' Percy forms an alliance with Welsh rebel Owain Glyndŵr.
- July 21 – Battle of Shrewsbury: King Henry IV of England defeats a rebel army led by "Hotspur" Percy, who is killed in the battle.
- October 7 – Battle of Modon: The Genoese fleet under Jean Le Maingre (Marshal Boucicaut) is defeated by the Republic of Venice, at Modon in the Peloponnese.
- Jan Hus begins preaching Wycliffite ideas in Bohemia.
- In China, the Yongle Emperor of the Ming Dynasty
- moves the capital from Nanjing to Beijing.
- commissions the Yongle Encyclopedia, one of the world's earliest and largest known general encyclopedias.
- orders his coastal provinces to build a vast fleet of ships, with construction centered at Longjiang near Nanjing; the inland provinces are to provide wood and float it down the Yangtze River.
- The Temple of a City God is constructed in Shanghai.
- The Gur-e Amir Mausoleum is built in Samarkand by Timur, after the death of his grandson Muhammad Sultan, and eventually becomes the family mausoleum of the Timurid Dynasty.
- Georgia makes peace with Timur, but has to recognise him as a suzerain and pay him tribute.
- The world's first quarantine station is built in Venice, to protect against the Black Death.
- Grand Duke Vytautas ends his alliance with Muscovy, and captures Vyazma and Smolensk.
- Stefan Lazarević establishes Belgrade, as the capital of the Serbian Despotate.
- A guild of stationers is founded in the City of London. As the Worshipful Company of Stationers and Newspaper Makers (the "Stationers' Company"), it continues to be a Livery Company in the 21st Century.
- In Ireland
- probable – Ououso becomes King of Nanzan, in present-day south Okinawa, Japan.
- January 2 – Basilios Bessarion, Latin Patriarch of Constantinople (d. 1472)
- February 22 – King Charles VII of France, monarch of the House of Valois, King of France from 1422 to his death (d. 1461)
- June 11 – John IV, Duke of Brabant, son of Antoine (d. 1427)
- September 1 – Louis VIII, Duke of Bavaria, German noble (d. 1445)
- September 25 – Louis III of Naples (d. 1434)
- September 29 – Elisabeth of Brandenburg, Duchess of Brzeg-Legnica and Cieszyn, German princess (d. 1449)
- date unknown
- March 8 – Beyazid, Ottoman Sultan (b. 1354)
- April 27 – Maria of Bosnia, Countess of Helfenstein (b. 1335)
- April – Đurađ II Stracimirović, Serbian nobleman from the House of Balšić in Zeta
- May 10 – Katherine Swynford, Duchess of Lancaster, spouse of John of Gaunt
- May 12 – William de Lode, English prior
- July 21 (at the Battle of Shrewsbury)
- July 23 – Thomas Percy, 1st Earl of Worcester, English rebel (executed) (b. 1343)
- date unknown – Vukosav Nikolić, Bosnian nobleman (in battle)
- probable date – Hajji Zayn al-Attar, Persian physician