The 4th century was defined by the calendar of Earth as occurring from the year 301 through the year 400.
- The inhabitants of Vulcan engage in terrible and destructive wars including the use of atomic bombs, a result of the violent passions and emotions that govern the Vulcan people. It is a savage time, even by Earth standards. Myths from this period describe a terrifying weapon of war called the Stone of Gol that kills with the power of the mind. (TOS: "Balance of Terror", "Amok Time", "All Our Yesterdays"; TNG: "Gambit, Part II"; ENT: "Awakening")
- The Time of Awakening: Surak of Vulcan leads his people onto a path of peace and logic. (TOS: "Amok Time", "The Savage Curtain"; TNG: "Gambit, Part II"; ENT: "Awakening")
- A group of Vulcans who do not follow Surak's teachings of logic leave their homeworld in a wave of emigration. They will finally settle on the planets Romulus and Remus, coming to be known as the Romulans. (TOS: "Balance of Terror", "The Enterprise Incident"; TNG: "Unification II", "Gambit, Part II")
- The Debrune, an offshoot of the Romulans, establish an outpost on Barradas III. (TNG: "Gambit, Part I")
- According to Weyoun, "the Dominion has endured for two thousand years" as of 2372, i.e., since the 4th century. (DS9: "To the Death")
- The Vidiian Sodality in the Delta Quadrant is ravaged by a deadly viral disease called the Phage. The Vidiians survive only by harvesting organs from non-Vidiians to replace their own tissues. (VOY: "Phage")
|3rd century||Timeline||5th century|