864

By place

Europe

• Spring , Emperor Louis II (the Younger) marches with a Frankish army against Rome. While en route to the papal city, he becomes ill, and decides to make peace with Pope Nicholas I.
• July 25 , Edict of Pistres: King Charles the Bald orders defensive measures against the Vikings. He creates a large force of cavalry, which inspires the beginning of French chivalry.
• Viking raiders, led by Olaf the White, arrive in Scotland from the Viking settlement of Dublin (Ireland). He rampages the country, until his defeat in battle by King Constantine I.
• Robert the Strong, margrave of Neustria, attacks the Loire Vikings in a successful campaign. Other Viking raiders plunder the cities of Limoges and Clermont, in Aquitaine.
• King Louis the German invades Moravia, crossing the Danube River to besiege the civitas Dowina (identified, although not unanimously, with Devín Castle in Slovakia).
• Pepin II joins the Vikings in an attack on Toulouse. He is captured while besieging the Frankish city. Pepin is deposed as king of Aquitaine, and imprisoned in Senlis.
• September 13 , Pietro Tradonico dies after a 28-year reign. He is succeeded by Orso I Participazio, who becomes doge of Venice.
• King Alfonso III conquers Porto from the Emirate of Cordoba. This is the end of the direct Muslim domination of the Douro region.

Asia

• Jōgan eruption (Japan): Mount Fuji, located on Honshu Island, erupts for 10 days.
• Hasan ibn Zayd establishes the Zaydid Dynasty, and is recognized as ruler of Tabaristan (Northern Iran).

By topic

Religion

• The Christianization of Bulgaria begins: Boris I, Knyaz of the Bulgarian Empire, is converted to Orthodox Christianity. His family and high-ranking dignitaries accept the Orthodox faith at the capital, Pliska - from this point onwards the rulers of the Bulgarian Empire are known as ‘Tsars’ rather than ‘Khans’.

• Gu Quanwu, general of the Tang Dynasty (d. 931)
• Khumarawayh ibn Ahmad ibn Tulun, ruler of the Tulunid Dynasty (d. 896)
• Louis III, king of the West Frankish Kingdom (or 863)
• Muhammad ibn Ya'qub al-Kulayni, Muslim scholar (d. 941)
• Simeon I, ruler (tsar) of the Bulgarian Empire (or 865)
• Yúnmén Wényǎn, Chinese Zen master (or 862)

• September 13 , Pietro Tradonico, doge of Venice
• Al-Fadl ibn Marwan, Muslim vizier
• Al-Fadl ibn Qarin al-Tabari, Muslim governor
• Arnold of Gascony, Frankish nobleman
• Bi Xian, chancellor of the Tang Dynasty (b. 802)
• Ennin, Japanese priest and traveler
• Hucbert, Frankish nobleman (b. 820)
• Laura, Spanish abbess
• Lorcán mac Cathail, king of Uisneach (Ireland)
• Muhammad ibn al-Fadl al-Jarjara'i, Muslim vizier (or 865)
• Pei Xiu, chancellor of the Tang Dynasty (b. 791)
• Sancho II, count of Gascony (approximate date)
• Sergius I, duke of Naples
• Trpimir I, duke (knez) of Croatia
• Yahya ibn Umar, Muslim imam (or 865)