It was stated in Diane Duane's novel The Romulan Way
that the ancestors of the Romulans left ancient Vulcan when Surak was still alive, and apparently did so with his blessing, led by S'task. The Vulcan's Soul
books, by Josepha Sherman and Susan Schwartz, followed this account very closely.
But in the Vulcan trilogy in the fourth season of Enterprise
, we actually see Surak dying from radiation poisoning as a result of a nuclear attack by enemies who "march beneath the raptor's wings." The image of a raptor does strongly indicate that these enemies were intended by the writers to be the proto-Romulans....but how can they still be on Vulcan at the time of Surak's death? Is there any way to reconcile this?