Millennium Eruption of Mount Paektu
The blast forms Heaven Lake and dusts Japan with ash

In late 946 the volcano on today's China–North Korea border produced one of the most powerful eruptions in human history, forming the crater of Heaven Lake. Ash reached Japan, where chronicles recorded the ashfall.
Wikipedia (English) · 10th century
Meanwhile around the world (±25 years)
Europe
- c. 939 Eldgjá eruption — 7 years earlier
- 962 Coronation of Otto I — 16 years later
Eastern Europe & Russia
- 966 Baptism of Poland — 20 years later
Africa
- 969 Founding of Cairo — 23 years later
Americas
- c. 950–1250 Medieval Warm Period — 4 years later
Alive at the time
- Otto the Great (aged 34)
- Olga of Kiev (aged 26)
- Ferdowsi (aged 6)
- Hugh Capet (aged 6)
- Sviatoslav I (aged 4)
- Edgar the Peaceful (aged 3)