Mount Churchill eruption
Alaskan ash reaches the bogs of Ireland and Germany

In the winter of 852/853 an Alaskan volcano spread the White River Ash, later found as far as peat bogs in Ireland and Germany. One hypothesis holds that the disaster pushed ancestors of the Navajo and Apache to migrate far south.
Wikipedia (English) · 9th century
Meanwhile around the world (±25 years)
Europe
- 843 Treaty of Verdun — 9 years earlier
Eastern Europe & Russia
- c. 862 Calling of the Varangians — 10 years later
Africa
- 859 Fatima al-Fihri founds al-Qarawiyyin — 7 years later
Asia
- 868 The Diamond Sutra is printed — 16 years later
Alive at the time
- Charles the Bald (aged 29)
- Rurik (aged 22)
- Oleg the Wise (aged 7)
- Alfred the Great (aged 3)