|Ab urbe condita||1981|
|Balinese saka calendar||1149–1150|
|English Regnal year||12 Hen. 3 – 13 Hen. 3|
|Chinese calendar||丁亥年 (Fire Pig)|
3924 or 3864
— to —
戊子年 (Earth Rat)
3925 or 3865
|- Vikram Samvat||1284–1285|
|- Shaka Samvat||1149–1150|
|- Kali Yuga||4328–4329|
|Japanese calendar||Antei 2|
|Minguo calendar||684 before ROC|
|Thai solar calendar||1770–1771|
1354 or 973 or 201
— to —
1355 or 974 or 202
|Wikimedia Commons has media related to 1228.|
- Sukaphaa, the first Ahom king, establishes his rule in Assam. The Ahom kings reign for close to 600 years.
- April 25 – Conrad IV of Germany becomes titular King of Jerusalem, with Frederick II, Holy Roman Emperor as regent.
- June 28 – The Sixth Crusade is launched from Brindisi by Emperor Frederick II, after delays due to sickness and an excommunication from Pope Gregory IX.
- Baldwin II becomes emperor of the Latin Empire in Constantinople, with John of Brienne as regent.
- The Transylvanian town of Reghin is first mentioned, in a charter of Andrew II of Hungary.
- Spain: King James I of Aragon launches a major offensive against the Muslims in Majorca. The same year, in Murcia, confronted by increasing Christian pressure, the cadi (soon to be called emir), Ibn Hud al-Yamadi, denounces the Almohads and acknowledges the Abbasids as legitimate caliphs, in effect declaring independence. Other notable Christian success: Alfonso IX of León conquers Mérida.
- The city of Tournai emits its first recorded life annuity, thus confirming a trend of consolidation of public debts started ten years earlier, in Reims.
- The first evidence is uncovered of the use of the Knights Templar as cashiers by the king of England, to transfer safely important sums to the continent, using letters of exchange. This shows that large transfers could take place across Europe, even before the emergence of important networks of Italian merchant-bankers.
- January – Robert of Courtenay, emperor of the Latin Empire
- April 25 – Queen Isabella II of Jerusalem (b. 1212)
- June – Reginald de Braose, English rebel baron
- July 9 – Stephen Langton, Archbishop of Canterbury
- September 24 – Stefan the First-Crowned, King of Serbia
- date unknown – Aedh Ua Conchobair, King of Connacht
- Linehan, Peter (1999). "Chapter 21: Castile, Portugal and Navarre". In Abulafia, David (ed.). The New Cambridge Medieval History c.1198-c.1300. Cambridge University Press. pp. 668–699 . ISBN 0-521-36289-X.
- Picard, Christophe (2000). Le Portugal musulman (VIIIe-XIIIe siècle. L'Occident d'al-Andalus sous domination islamique. Paris: Maisonneuve & Larose. p. 110. ISBN 2-7068-1398-9.
- Zuijderduijn, Jaco (2009). Medieval Capital Markets. Markets for renten, state formation and private investment in Holland (1300-1550). Leiden/Boston: Brill. ISBN 978-9-00417565-5.
- Ferris, Eleanor (1902). "The Financial Relations of the Knights Templars to the English Crown". American Historical Review. 8 (1).
- "Conrad IV | king of Germany". Encyclopedia Britannica. Retrieved February 14, 2020.