The 4th century
1,523 sourced entries across 100 documented years, grouped into 10 decades. A century here runs 1900–1999 rather than 1901–2000, so its decades sit inside it exactly.
Decades
- The 300s — 10 years, 176 entries
- The 310s — 10 years, 143 entries
- The 320s — 10 years, 116 entries
- The 330s — 10 years, 139 entries
- The 340s — 10 years, 123 entries
- The 350s — 10 years, 150 entries
- The 360s — 10 years, 170 entries
- The 370s — 10 years, 178 entries
- The 380s — 10 years, 181 entries
- The 390s — 10 years, 147 entries
By subject
- Conflict & Security in the 4th century — 236 entries
- Religion & Belief in the 4th century — 231 entries
- Geopolitics & Diplomacy in the 4th century — 72 entries
- Culture & Society in the 4th century — 39 entries
- Exploration & Expansion in the 4th century — 37 entries
- Crime & Justice in the 4th century — 20 entries
- Technology & Infrastructure in the 4th century — 18 entries
- Climate & Environment in the 4th century — 17 entries
- Science & Discovery in the 4th century — 16 entries
- Health & Medicine in the 4th century — 14 entries
A few of the years
- 301September 3 – The republic of San Marino is established (approximate date).
- 314January 10 – Pope Miltiades' reign ends.
- 326September 14 (traditional date) – Helena, mother of Constantine I, discovers the so-called True Cross and the Holy Sepulchre (Jesus's tomb) in Jerusalem. On her pilgrimage, which begins about this year, she pauses on the Aegean island of Patmos, where she is said to found the church of Panagia Ekatontapiliani.
- 338Eusebius of Nicomedia becomes Patriarch of Constantinople, after Paul I is banished.
- 350January 18 – Western Roman Emperor Constans I makes himself extremely unpopular; one of his generals, Magnentius, is proclaimed emperor at Augustodunum in the Diocese of Galliae, with the support of the army on the Rhine frontier.
- 362February 21 – Athanasius returns to Alexandria and convenes a council, at which he appeals for unity among Christians who differ in terminology, but Emperor Julian orders Athanasius to leave Alexandria. He will remain in exile in Upper Egypt, until after Julian's death the next year.
- 374May 4 – Spearthrower Owl ascends to the throne and becomes ruler of Teotihuacan (Mexico).
- 386Saint Ambrose defends the rights of the Catholic Church with respect to those of the State.