From Wikipedia, the free encyclopedia
|Centuries:||12th century – 13th century – 14th century|
|Decades:||1200s 1210s 1220s – 1230s – 1240s 1250s 1260s|
|Years:||1228 1229 1230 – 1231 – 1232 1233 1234|
|1231 by topic|
|State leaders – Sovereign states|
|Birth and death categories|
|Births – Deaths|
|Establishments and disestablishments categories|
|Establishments – Disestablishments|
|Art and literature|
|1231 in poetry|
|Ab urbe condita||1984|
|English Regnal year||15 Hen. 3 – 16 Hen. 3|
— to —辛卯年十二月初七日
|- Vikram Samvat||1287–1288|
|- Shaka Samvat||1153–1154|
|- Kali Yuga||4332–4333|
|- Ǹrí Ìgbò||231–232|
|Juche calendar||N/A (before 1912)|
|Julian calendar||1231 MCCXXXI|
|Minguo calendar||681 before ROC
|Thai solar calendar||1774|
|Wikimedia Commons has media related to: 1231|
By area 
- April 9 – After a bizarre weather phenomena of yellowish clouds and dust chokes the air around Hangzhou, Song Dynasty, China, obscuring the sky and sun, a fire breaks out at night in the southeast of the city, which continues into the next day. Fighting the flames is difficult due to limited visibility. When the fires are extinguished, it is discovered that an entire district of some 10,000 houses in the southeast of the city were consumed by the flames.
- Mongol troops cross the Yalu River into Korea, then under the Goryeo Kingdom.
- Italy: Emperor Frederick II promulgates the Constitutions of Melfi (also known as Liber Augustalis), a collection of laws for Sicily.
- Italy: The Pandorica is donated to the Vatican
- Llywelyn the Great launches a campaign against the Norman lordships in Wales.
- Spain: The Castillans reconquer the city of Quesada.
By topic 
- March 17 – Emperor Shijō of Japan (d. 1242)
- Guo Shoujing, Chinese astronomer and mathematician
- John de Warenne, 6th Earl of Surrey (d. 1304)
- Roger Mortimer, 1st Baron Wigmore (d. 1282)
- April 6 – William Marshal, 2nd Earl of Pembroke
- June 13 – Anthony of Padua, Portuguese saint (b. 1195)
- November 6 – Emperor Tsuchimikado of Japan (b. 1196)
- November 17 – Saint Elisabeth of Hungary, daughter of Andrew II of Hungary (b. 1207)
- Abd al-Latif al-Baghdadi, Arab physician and traveller