2000 years (By TNG.). The age of enlightenment. Saurek said Logic, the old guard said "no thank you" which was not an option. A nuclear war started. The old Guard left, founded the Romulan Star Empire and the Vulcans wallowed in a radioactive wasteland mutating horribly as their brow ridges receded pushing their brains out their ear holes like how one makes play dough spaghetti with a fun factory.
(Actually? The radiation from the war might have given the Vulcans their impressive mental abilities which Romulans have NEVER been seen to exhibit. Of course according to the Kirshara, Surak was already a telepath... But then maybe the age of Enlightenment, the atomic war lasted a century or two? No. Logic was invented as religion to cancel the impressively destructive telepathic weapons that were en vogue during the age of Surak. Never mind.)
Think about it. The Vucans didn't win their homeworld. They were left there to die. The winning side who had not just a fleet, but an armada that could be retrofitted into a generational colony fleet that went looking for a planet at sublight speeds that could support them.
Can you imagine the communication by radio for the first 20 years it took the Romulan fleet to clear the Vulcanian Solar system... "Hey, you ass hats back on Vulcan! Dead yet? Ha! ha! Fuck ya!"