Little is really known of Romulus’s origin’s. Although, it's believed that Romulus is the first specimen of "Lupus Sapiens", which is an old species of beings that have evolved from wolves instead of apes. He has been alive for thousands of years and has been seen in Wolverines dreams fighting prehistoric men and as an Emperor of the Roman Empire.
Nick Fury also revealed to Wolverine that Romulus has been manipulating Wolverine's family bloodline for centuries. He's was also the one responsible for taking Daken, Wolverine's son from his dead mother's womb and raised him to become a ruthless killer. He's also the one responsible for lying to Daken that Wolverine killed his mother.