Around the fourth century, Vulcans who rejected Surak's logic left their homeworld and eventually settled Romulus, founding the Romulan people.
Not every Vulcan followed Surak during the Time of Awakening. A faction who refused to give up their passions left Vulcan aboard ships and travelled far into space. Their descendants settled on Romulus and became the Romulans, who kept their common origin hidden from much of the galaxy.
Humans learned of the shared ancestry in 2266, when Spock saw a Romulan commander for the first time. In 2368 Spock went to Romulus to support an underground movement that sought reunification, believing that the two peoples might one day be reconciled.