|Centuries:||4th century – 5th century – 6th century|
|Decades:||390s 400s 410s – 420s – 430s 440s 450s|
|Years:||419 420 421 – 422 – 423 424 425|
- End of the Roman–Sassanid War: Emperor Theodosius II signs a 100-year peace treaty with Persia after 2 years of war. Both give freedom of religion in their territories.
- March 3 – Theodosius II issues a law to form provisions in peacetime. Theodosius pays an annual tribute of 350 pounds of gold to the Huns to buy peace.
- Theodosius II receives a statue at Hebdomon. On its base (fragments are now in the Istanbul Archaeology Museum), writing praises him as “everywhere and forever victorius.”
- The walls of Rome's Flavian Amphitheater (Colosseum) crack during an earthquake.
- Shao Di, age 16, eldest son of Wu Di succeeds his father as emperor of the Liu Song Dynasty (China).