The Romulan Empire

Federation citizens are strictly prohibited from crossing the Romulan neutral zone. Any penetration of the zone by either side may be construed as an act of war. The Romulans are reputed to be an offshoot of the Vulcan race, descendants of those who rejected the pacifist teachings of the Vulcan Surak some two thousand years ago and struck out into space seek a new home. Eventually, they established their settlements on Romulus and Remus, now considered their homeworlds.

Since no alliance is established between the Federation and The Romulan. not much is known about their culture and technology. Although based on Starfleets encounter with Romulan vessels there seem to be only three types of ships used by the Romulans:

The Romulan Bird of Prey

The Romulan Scout Ship

The Romulan Warbird