321 CE
Constantine I signs legislation directing urban residents to refrain from work, and businesses to be closed, on the "venerable day of the Sun". An exception is made for agriculture. Constantine I assigns convicts to grind Rome's flour, in a move to hold back the rising price of food in an empire whose population has shrunk as a result of plague. History of the Jews in Germany: Jews in modern-day Germany are documented for the first time, in Colonia Agrippinensium (modern-day Cologne).
Conflict & Security
- Tuoba Heru launches a coup d'état against his cousin Tuoba Yulü and becomes the new Prince of Dai.source
Exploration & Expansion
- Emperor Constantine I expels the Goths from the Danube frontier and repairs Trajan's Bridge. He leads an expedition into the old province Dacia (modern Romania) and makes peace with the barbarians.source
- History of the Jews in Germany: Jews in modern-day Germany are documented for the first time, in Colonia Agrippinensium (modern-day Cologne).source
Religion & Belief
Health & Medicine
- March 7 - Constantine I signs legislation directing urban residents to refrain from work, and businesses to be closed, on the "venerable day of the Sun". An exception is made for agriculture.source
- Constantine I assigns convicts to grind Rome's flour, in a move to hold back the rising price of food in an empire whose population has shrunk as a result of plague.source