Is this my nerdiest post? Yes. Anyway,
The Star Trek wiki had something interesting...
Paul Schneider modeled the Romulans on the ancient Romans, naming the species' homeworlds after the mythical founders of Rome, Romulus and Remus. "It was a matter of developing a good Romanesque set of admirable antagonists that were worthy of Kirk," Schneider related. "I came up with the concept of the Romulans which was an extension of the Roman civilization to the point of space travel, and it turned out quite well." (Captains' Logs: The Unauthorized Complete Trek Voyages, p. 34) D.C. Fontana reckoned that Schneider basing the aliens on the pre-existing Roman civilization was the cause for the writer receiving insufficient credit for creating the Romulans. ("Balance of Terror" Starfleet Access, TOS Season 1 Blu-ray) Gene Roddenberry, interested in ancient Rome himself, approved of the initial depiction of the Romulan species. "He loved Paul's having endowed the enemy-Romulans with the militaristic character of the ancient Romans," wrote John D.F. Black and Mary Black. (Star Trek: The Magazine Volume 2, Issue 11, p. 19) Roddenberry's original concept of the Romulans, however, was that they represented 1960s' Chinese Communists.
Yes, Romulans are somewhat based on the Roman Empire and are xenophobic conquerers, but Westerners often ignorantly attribute these traits to communist countries anyway.
Then there is the Klingons, again, the Klingons are nothing like communists, (they're a patriarchal empire) and yet I've seen people say they were based on the Soviets.
So what do you think?
I have two somewhat incompatible ideas about klingons
when i was watching one of the newer "viking" TV shows it was like watching one of the klingon court intrigue episodes. then someone told me klingons were meant to be like vikings but I never looked into if that was at all true but I tihnk it's funny.
It almost seems like "klingon" doesn't refer to a species so much as a class, ethnicity or subculture of a minority within a species. it isn't plausible for all the attitudes about "what is a klingon" to be pervasive through a large population. you need to own land. you need to have something to do with the high council which is like 8 people. you can't have an even nominally productive job. famers, lawyers, cooks, scientists: all are disgraced.
we do occasionally meet people who don't fit that mold but they spend the whole time crying about how they are outcasts from "klingon society" but it would really be like 95% of people. OTOH if "klingon" was just a single, small group that was extremely powerful it would make more sense. "klingon" is a group more like "catholic clergy" than like "humans".
Klingons were retconned during the TOS movie Era from what they were in the original TV show to more or less what we see in TNG. TOS is incongruent with later trek in many ways.