|Covid-19|February 26 – Mongol–Jin War: The Mongols capture Kaifeng, the capital of the Jin dynasty, after besieging it for months.
December – Mongol siege of Caizhou begins.
Winter – Spain: after the loss of Trujillo and Úbeda, Ibn Hud al-Yamadi has to demand a truce to the king of Castile Ferdinand III.
The Castilian troops besiege the Muslim-held city of Peniscola.
The rebellious city of San Severo is destroyed by Frederick II, Holy Roman Emperor.
Elburg and Gendt get their city rights.
Amadeus IV becomes count of Savoy.
Pope Gregory IX forbids Jews to employ Christian servants.
Mustansiriya Madrasah is founded in Baghdad.
Al-Nawawi, Syrian writer (d. 1278)
Ibn Manzur, Libyan lexicographer (d. 1311)
March 1 – Thomas, Count of Savoy (b. 1178)
March – Bohemond IV of Antioch (b. ca. 1172)
June – Gökböri, Muslim emir and general (b. 1154)
Aedh mac Ruaidri Ó Conchobair, King of Connacht
Ali ibn al-Athir, Arab historian (b. 1160)
John Apokaukos, Byzantine bishop (b. ca. 1155)
Year 1233 (MCCXXXIII) was a common year starting on Saturday (link will display the full calendar) of the Julian calendar.