The 3rd century

1,306 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 200s — 10 years, 139 entries
The 210s — 10 years, 146 entries
The 220s — 10 years, 126 entries
The 230s — 10 years, 125 entries
The 240s — 10 years, 124 entries
The 250s — 10 years, 168 entries
The 260s — 10 years, 129 entries
The 270s — 10 years, 144 entries
The 280s — 10 years, 108 entries
The 290s — 10 years, 97 entries

By subject

Conflict & Security in the 3rd century — 247 entries
Geopolitics & Diplomacy in the 3rd century — 90 entries
Religion & Belief in the 3rd century — 80 entries
Crime & Justice in the 3rd century — 36 entries
Exploration & Expansion in the 3rd century — 29 entries
Culture & Society in the 3rd century — 28 entries
Economy & Finance in the 3rd century — 13 entries
Technology & Infrastructure in the 3rd century — 12 entries
Health & Medicine in the 3rd century — 11 entries
Climate & Environment in the 3rd century — 9 entries
Science & Discovery in the 3rd century — 9 entries

A few of the years

200September-November - Battle of Guandu: Chinese warlord Cao Cao defeats his rival Yuan Shao.
212The edict of Emperor Caracalla (Constitutio Antoniniana) extends Roman citizenship to all free inhabitants of the Roman Empire, with the exception of a limited group that may include Egyptians. The Jewish people are among those who receive citizenship. All free women in the Empire are given the same rights as Roman women.
224January 1 – Gaius Bellicius Torquatus and Appius Claudius Julianus II begin their one year terms as the new Roman consuls.
236January 10 – Pope Fabian succeeds Pope Anterus as the twentieth pope.
248Jungcheon becomes ruler of the Korean kingdom of Goguryeo (until 270).
260King Shapur I sends Valerian to Bishapur and uses the captured Roman army for engineering plans. They construct the Band-e Kaisar ("Bridge of Valerian").
272Aurelian supports the bishops of Italy in deposing the bishop of Antioch, Paul of Samosata, who had been a supporter of Zenobia. This is the first recorded instance of an imperial intervention in an ecclesiastical dispute.
286Emperor Diocletian campaigns successfully against Sarmatian raids. The future emperor Constantius defeats the 'Bosporian Sarmatians'.