Though it isn't spelled out exactly, Surak kind of told Archer this when he carried his katra in the Vulcan arc in Enterprise
(probably in the episode "Awakening"). They look out on a landscape devastated by nuclear war and Surak tells him that those who rejected his teachings violently were "marching under raptor's wings" which is a reference to the symbol the Romulans still use as their national symbol.
Also, in TOS (in "Balance of Terror") Spock theorises that the Romulans are an off-shoot of the Vulcans that left because they rejected logic. This had been just a myth to him until he saw the face of the Romulan commander.