The Years of Chaos was the name given to the violent turbulent times on the planet Vulcan when its inhabitants waged constant and devastating wars on its surface. This era in Vulcan history only ended by the intervention of Surak who preached his philosophy of logic that transformed his civilization into a peaceful species.
Abraham Dannon during the final years of the Earth-Romulan War commented that all wars ultimately ended and gave examples of Andoria's, Vulcan's and Earth's histories being examples of this fact. This was part of his famous Sighted Man of Peace speech that brought about a resolution of the conflict with the Romulan Star Empire by offering a peace treaty to their foes. (FASA RPG module: The Romulan War)