|833 by topic|
|Ab urbe condita||1586|
|Balinese saka calendar||754–755|
|Chinese calendar||壬子年 (Water Rat)|
3529 or 3469
— to —
癸丑年 (Water Ox)
3530 or 3470
|- Vikram Samvat||889–890|
|- Shaka Samvat||754–755|
|- Kali Yuga||3933–3934|
|Japanese calendar||Tenchō 10|
|Minguo calendar||1079 before ROC|
|Seleucid era||1144/1145 AG|
|Thai solar calendar||1375–1376|
959 or 578 or −194
— to —
960 or 579 or −193
Year 833 (DCCCXXXIII) was a common year starting on Wednesday (link will display the full calendar) of the Julian calendar.
- Byzantine-Arab War: Emperor Theophilos signs an armistice for peace with the Abbasid Caliphate. He offers Caliph Al-Ma'mun 100,000 gold dinars, in return for 7,000 Byzantine prisoners.
- June – Lothair I, eldest son of Emperor Louis the Pious, joins the rebellion of his brothers Pepin I and Louis the German, with the assistance of Archbishop Ebbo. Louis is forced to abdicate, on the plains of Rothfield (near Colmar).
- Mojmir I, Moravian duke, expels Prince Pribina from his homeland (western part of modern Slovakia). He unifies Great Moravia and becomes the first known ruler of the Moravian Slavs, who founds the House of Mojmir (approximate date).
- Galindo Aznárez I, Frankish count, usurps the Catalan counties (pagi) of Pallars and Ribagorza, in the Spanish March (modern Spain), a buffer zone between the Pyrenees and the Ebro River.
- August 7 – Caliph Al-Ma'mun dies after a 20-year reign. He is succeeded two days later by his half-brother al-Mu'tasim, as ruler of the Abbasid Caliphate.
- Ibn Hisham, Muslim historian, collects oral traditions that form the basis for the biography of the Islamic prophet Muhammad.
- Emperor Junna abdicates the throne, after a 10-year reign. He is succeeded by his nephew Nimmyō, as the 54th emperor of Japan.
- Irmgard, Frankish abbess (or 830)
- Kocel, Slavic prince (approximate date)
- Luo Yin, Chinese statesman and poet (d. 910)
- Yi Zong, emperor of the Tang Dynasty (d. 873)
- May 7 – Ibn Hisham, Muslim historian
- July 20 or 834 – Ansegisus, Frankish abbot
- August 9 – Al-Ma'mun, Muslim caliph (b. 786)
- Conchobar mac Donnchada, High King of Ireland
- Diarmait mac Tommaltaig, king of Connacht (Ireland)
- Dou Yizhi, chancellor of the Tang Dynasty
- Du Yuanying, chancellor of the Tang Dynasty (b. 769)
- Enravota, ruler of the Bulgarian Empire (approximate date)
- García Galíndez (the Bad), count of Aragon
- Nagabhata II, ruler of the Gurjara-Pratihara Dynasty
- Song Shenxi, chancellor of the Tang Dynasty
- Yuthog Yontan Gonpo, Tibetan high priest (b. 708)
- ^ J. Norwich, Byzantine: The Apogee, p. 47.