891

Year 891 (DCCCXCI) was a common year starting on Friday (link will display the full calendar) of the Julian calendar.

Europe

 * February 21 – Guy III, duke of Spoleto, is crowned Holy Roman Emperor by Pope Stephen V. His son Lambert is proclaimed king of Italy, at the capital of Pavia in Lombardy.
 * Summer – Orso, Lombard prince of Benevento, is deposed after the capture of Benevento by the Byzantines. Benevento becomes the capital of the thema of Longobardia.
 * Battle of Leuven: Viking raiders on the Dyle River (near Leuven), in modern-day Belgium, suffer a crushing defeat by Frankish forces under King Arnulf of Carinthia.

Emirate of Córdoba

 * Muslim forces led by Abdullah ibn Muhammad al-Umawi, Umayyad emir of Córdoba, defeat the rebel leader Umar ibn Hafsun at Poley, in Al-Andalus (modern Spain).

Arabian Empire (Caliphate)

 * June 2 – Al-Muwaffaq, an Abbasid prince and Commander-in-chief, dies at the capital of Baghdad. His son Al-Mu'tadid is recognized as regent, and second heir of the Abbasid Caliphate.

Japan

 * February 25 – Fujiwara no Mototsune, a Japanese statesman, dies. In his lifetime, he had forced the resignation of Emperor Yōzei and become head of the Fujiwara clan.

Religion

 * September 14 – Pope Stephen V dies after a 6-year reign. He is succeeded by Formosus, former cardinal bishop of Portus, as the 111th pope of the Catholic Church.

Births

 * Abd al-Rahman III, Umayyad caliph (or 889)
 * Ali ibn Buya, founder of the Buyid Dynasty (or 892)
 * Gao Conghui, prince and ruler of Jingnan (d. 948)
 * Lin Ding, Chinese official and chancellor (d. 944)
 * Yuan Dezhao, Chinese chancellor (d. 968)

Deaths

 * February 25 – Fujiwara no Mototsune, Japanese regent (b. 836)
 * June 2 – Al-Muwaffaq, Abbasid prince and regent (b. 842)
 * June 25 – Sunderolt, archbishop of Mainz
 * September 14 – Stephen V, pope of the Catholic Church
 * October 23 – Yazaman al-Khadim, Abbasid emir
 * Bernard, illegitimate son of Charles the Fat (or 892)
 * Chen Yan, Chinese warlord and governor
 * Enchin, Japanese Buddhist monk (b. 814)
 * Gu Yanlang, Chinese warlord and governor
 * Isma'il ibn Bulbul, Abbasid official and vizier
 * Mutimir of Serbia, ruler of Principality of Serbia
 * Wang Hui, chancellor of the Tang Dynasty