|Centuries:||8th century – 9th century – 10th century|
|Decades:||850s 860s 870s – 880s – 890s 900s 910s|
|Years:||877 878 879 – 880 – 881 882 883|
- Oldest known mention of the city of Dortmund
- Pope John VIII issued the Bill "Industriae Tuae", creating an independent ecclesiastical province in Great Moravia with Archbishop Saint Methodius as its head. The Old Church Slavonic was recognized as the fourth liturgical language, besides Latin, Greek and Hebrew.
- Bishopric established in Nitro.