| 293 | Diocletian creates the tetrarchy |
| 301 | Diocletian issues Edict on Maximum Prices and Wages |
| 303 | Diocletian launches Great Persecution of Christians |
| 312 | Constantine sees vision, wins battle of the Milvian Bridge in Rome, and converts to Christianity |
| 313 | Religious freedom is proclaimed in the Edict of Milan |
| 323 | Pachomius in Upper Egypt establishes the first monasteries |
| 324 | Constantine wins civil war and re-founds Byzantium as Constantinople, the “New Rome” |
| 325 | Council of Nicaea defends Christian orthodoxy against Arianism |
| 361–363 | Julian the Apostate tries to reinstate polytheism as official state religion |
| 378 | Barbarian massacre of Roman army in battle of Adrianople |
| 391 | Theodosius I makes Christianity the official state religion |
| 395 | Theodosius I divides empire into western and eastern halves |
| 410 | Visigoths sack Rome |
| 426 | Augustine publishes The City of God |
| 451 | Council of Chalcedon attempts to forge agreement on Christian orthodoxy |
| 475 | Visigoths publish law code |
| 476 | German commander Odoacer deposes the final western emperor, the boy Romulus Augustulus (“the fall of Rome”) |
| 493–526 | Ostrogothic kingdom in Italy |
| 507 | Clovis establishes Frankish kingdom in Gaul |
| 527–565 | Reign of eastern Roman emperor Justinian |
| 529–534 | Justinian publishes law code and handbooks |
| 540 | Benedict devises his rule for monasteries |