864

864 in various calendars
Gregorian calendar	864; DCCCLXIV
Ab urbe condita	1617
Armenian calendar	313; ԹՎ ՅԺԳ
Assyrian calendar	5614
Balinese saka calendar	785–786
Bengali calendar	271
Berber calendar	1814
Buddhist calendar	1408
Burmese calendar	226
Byzantine calendar	6372–6373
Chinese calendar	癸未年 (Water Goat); 3561 or 3354; — to —; 甲申年 (Wood Monkey); 3562 or 3355
Coptic calendar	580–581
Discordian calendar	2030
Ethiopian calendar	856–857
Hebrew calendar	4624–4625
Hindu calendars
- Vikram Samvat	920–921
- Shaka Samvat	785–786
- Kali Yuga	3964–3965
Holocene calendar	10864
Iranian calendar	242–243
Islamic calendar	249–250
Japanese calendar	Jōgan 6; (貞観６年)
Javanese calendar	761–762
Julian calendar	864; DCCCLXIV
Korean calendar	3197
Minguo calendar	1048 before ROC; 民前1048年
Nanakshahi calendar	−604
Seleucid era	1175/1176 AG
Thai solar calendar	1406–1407
Tibetan calendar	阴水羊年; (female Water-Goat); 990 or 609 or −163; — to —; 阳木猴年; (male Wood-Monkey); 991 or 610 or −162

Millennium:	1st millennium
Centuries:	8th century; 9th century ; 10th century;
Decades:	840s; 850s; 860s ; 870s; 880s;
Years:	861; 862; 863; 864 ; 865; 866; 867;

Year 864 (DCCCLXIV) was a leap year starting on Saturday (link will display the full calendar) of the Julian calendar.

Events

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).^[1]^[2]
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.^[3]

Mount Fuji, located on Honshu Island, erupts for 10 days, in an event known as the Jōgan eruption (Japan).
Hasan ibn Zayd establishes the Zaydid Dynasty, and is recognized as ruler of Tabaristan (Northern Iran).^[4]

The Christianization of Bulgaria begins: Boris I, ruler (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’.^[5]

^ Bowlus, Charles R. (1995). Franks, Moravians, and Magyars: The Struggle for the Middle Danube, 788-907 (Illustrated ed.). University of Pennsylvania Press, Incorporated. p. 140. ISBN 978-0-8122-3276-9.
^ Goldberg, Eric Joseph (2006). Struggle for Empire: Kingship and Conflict Under Louis the German, 817-876 (Illustrated, reprint ed.). Cornell University Press. p. 273. ISBN 978-0-8014-3890-5.
^ Picard, Christophe (2000). Le Portugal musulman (VIIIe-XIIIe siècle0. L'Occident d'al-Andalus sous domination islamique. Paris: Maisonneuve & Larose. p. 109. ISBN 2-7068-1398-9.
^ Buhl, Fr. (1986). Bearman, P.; Bianquis, Th.; Bosworth, C. E.; van Donzel, E.; Heinrichs, W. P. (eds.). "al-Ḥasan b. Zayd b. Muḥammad". The Encyclopaedia of Islam (2nd ed.). Brill: 245.
^ Karloukovski, Vassil (1927). "V. Zlatarski - Istorija 1 B - 3.2". Promacedonia.org. Retrieved August 26, 2017.