Romulans are similar to Vulcans. They are a Warrior species from the planets Romulus and Remus. Romulans left Vulcan two thousand years ago and founded the Romulan Star Empire. Romulans are sly, sneaky, crafty, proud, and often aggresive and violent. A war between Romulans and Earth in 2160, resulted in the Romulan Neutral Zone. No ship is allowed to cross the Romulan Neutral Zone, if they did it would be considered an act of war. The Neutral Zone remained unviolated until Romulan Bird of Prey crossed it. Later the Romulans had a short alliance with the Klingon Empire, which resulted in a sharing of technology. Romulan activity heated up in 2364 because of the Borg. In the "present" time in Star Trek, the Romulans are allies with Klingon