Division of the Roman Empire
East and West part ways: one falls, the other lasts 1,000 years

On the death of Theodosius I, the last emperor to rule the whole empire, it was permanently split between his sons: Arcadius took the East and Honorius the West. The West fell 81 years later, while the East (Byzantium) endured another thousand years.
Wikipedia (Russian) · Wikipedia (English) · 4th century
Meanwhile around the world (±25 years)
Middle East
- c. 405 Mesrop Mashtots creates the Armenian alphabet — 10 years later
Alive at the time
- Augustine of Hippo (aged 41)
- Hypatia (aged 35)