From Infogalactic: the planetary knowledge core
|Centuries:||8th century – 9th century – 10th century|
|Decades:||840s 850s 860s – 870s – 880s 890s 900s|
|Years:||867 868 869 – 870 – 871 872 873|
|870 by topic|
|State leaders – Sovereign states|
|Birth and death categories|
|Births – Deaths|
|Establishment and disestablishment categories|
|Establishments – Disestablishments|
|Ab urbe condita||1623|
|Chinese calendar||己丑年 (Earth Ox)
3566 or 3506
— to —
庚寅年 (Metal Tiger)
3567 or 3507
|- Vikram Samvat||926–927|
|- Shaka Samvat||792–793|
|- Kali Yuga||3971–3972|
|Japanese calendar||Jōgan 12
|Minguo calendar||1042 before ROC
|Seleucid era||1181/1182 AG|
|Thai solar calendar||1412–1413|
- Prague Castle is founded.
- The Great Summer Army invades England led by Bagsecg and conquers East Anglia; the buildings destroyed by the Danish invaders include the abbey of Ely and the monastery of Peterborough.
- August 8 – Treaty of Meerssen: Charles the Bald and Louis the German divide Lotharingia among themselves.
- December 31 – The Danes are defeated by a Saxon army at Englefield, Berkshire. It is the first of a series of battles between Wessex and the Danes.
- Malta is conquered by Arabs from Sicily.
- Borivoj becomes duke of Bohemia.
- Charles the Bald marries Richilde.
- Michael II succeeds Michael I as Patriarch of Alexandria.
- The Autonomous Bulgarian Archbishopric is established.
- Christianization of the Serbs
- February 28 – The Fourth Council of Constantinople ends.
- November 20 – King Edmund the Martyr
- Muhammad ibn Ismail al-Bukhari, Persian hadith compiler
- Al-Kindi, philosopher