Just want to add that the Romulan empire is CLEARLY a representation of the Roman empire, nothing at all to do with "east Asian" cultures. Their planets are called Romulus and Remus, they have "Centaurions", etc. It is very obvious in that case. The analogy of Klingons as Soviets is accurate though.
Based on the many references it seems the Romulans are heavily based on the Roman Empire.
...the dread of something after death. The undiscovered country from whose bourne no travelers returns...
Hamlet Act III scene 1. This phrase is part of the speech that begins with the famous words "To be or no to be". In the movie Kirk described the undiscovered country to be the future, but Hamlet is actually refering to death and the possibility of life after death.
The Romulan/Roman connection is pretty clear. However, I never felt that the Romulans embodied the ruthlessness or brutality of the Roman Empire. Study the Roman combat tactics and you'll see what I mean. The Romans used a short stabbing weapon, the Gladius. They did not fence with opponents. They blocked your initial attack with their large shield, then stabbed you with three lighting attacks. They stabbed you in the femoral artery, the groin, and the stomach then marched on as you bleed to death. Roman soldiers were efficient and deadly.
The tentions between the Klingons and the Federation are similar to the Cold War tentions between the Warsaw Pact and NATO. However, the Klingons definately have an Asian element to them. Remember that China was also a strong player in the Cold War. The Klingon's sense of honor and their "Way of the Warrior" attitude is definately a reference to the Japanese Samurai's Bushido. In TNG "Second Chances", Thomas Riker comments on how similar the Klingon martial arts are to Tai Chi Chuan (a Chinese form of martial arts). Admiral William Thomas Riker 21:22, July 26, 2011 (UTC)