Like the Vulcans the Romulans have surrendered unrestrained violence as a way of life. However, in the case of the Romulans this has been replaced with a controlled deviousness; as a species the Romulans are generally thought of as duplicitous, a reputation the actions of their government over the last decade has reinforced. Their reluctance to rely on overt hostility generally leads the Romulans to play a waiting game, attempting to manipulate an opponent into breaking - or appearing to break - an agreement so as to give them a solid justification for striking.

Once the planet Romulus was colonised, the Romulans rapidly spread to their systems second habitable planet, Remus. From their they founded an interstellar empire spanning dozens of worlds. In the 2150's this empire came into contact with the rapidly expanding Human sphere of influence, and a brief but intense war resulted. This war was fought entirely in space, without any kind of personal or visual interaction between the two sides; no Human or Vulcan saw a Romulan until 2266, long after the war was ended, when a Romulan warbird penetrated the Neutral Zone to test Federation defences. Although the ship was destroyed by the USS Enterprise, this action marked a long period of 'cold war' between the two powers. Eventually this culminated in the Tomed Incident of 2311, when thousands of Federation lives where lost ot the Romulans. The incident led to the Treaty of Algeron, which forbade the Federation from developing cloaking technology and reaffirmed the existence of the Neutral Zone between the two powers. Subsequent to this the Romulans cut off all contact with the Federation.

Although the Starship USS Enterprise-C engaged several Romulan vessels attacking the khittomer outpost in 2344, in general the Romulans maintaind their isolation until 2344. At this point a Romulan warbird entered Federation space to investigate the loss of several of their border outposts. Although it later emerged that the Borg where responsible for the destruction, the Romulans announced at this time that they would again take a more active role in international relations. They acted in opposition to the Federation for some years, until the emergence of the Dominion threat in 2370. The Romulans responded by allowing the Federation to utilise one of their cloaking devices on the USS Defiant in order to allow it to operate in the Gamma Quadrant.

Subsequently the Romulan Tal'Shiar launched a joint attack on the Dominion with the Cardassian Obsidian Order; the attack failed utterly, devastating the Romulan and Cardassian fleets. After this the Romulan government signed a non-agression pact with the Dominion. Recently the Romulans have reneged on this treaty and joined forces with the Federation-Klingon alliance in the war against the Dominion.