|Centuries:||3rd century – 4th century – 5th century|
|Decades:||300s 310s 320s – 330s – 340s 350s 360s|
|Years:||333 334 335 – 336 – 337 338 339|
- Emperor Constantine I is able to gain back most of Dacia for the Roman Empire.
- The first recorded customs tariff is in use in Palmyra.
- January 18 – Pope Mark succeeds Pope Sylvester I as the 34th pope.
- Pope Mark begins to build the basilica of San Marco. The church is devoted to St. Mark.
- Arius, Alexandrian priest, collapses in the street at Constantinople (approximate date).
- Pope Mark dies at Rome after an 11-month reign. No successor is immediately found.
- for more information, see Category:336 deaths.