I've been revising my fantasy story's world severely, and now it features the following five cultures, all of which have real world inspirations: 1. A Northern European "barbarian" tribe with longships. The heroine's male love interest, a warrior with a score to settle, comes from this culture. 2. A maritime civilization of olive-skinned people similar to ancient Greeks and Romans. They function as minor antagonists. 3. A matriarchal Black African civilization with an Egyptian/Nubian flavor. The heroine is the Queen of this culture. 4. A desert-dwelling Middle Eastern culture ruled by a tyrannical sheikh/prophet who is the story's major antagonist. 5. A technologically advanced but war-torn Chinese/Japanese civilization that is the only culture in the world to have gunpowder. I used to be a big fan of what TVTropes calls Fantasy Counterpart Cultures, but I've heard people complain that they're unimaginative. I don't plan to have each of my cultures match their real-world analogs in every single way, and of course some of these cultures are combinations of more than one real culture, but still I wonder if I should make my cultures more unique. What do you think about Fantasy Counterpart Cultures?
The goal when using Fantasy Counterpart Cultures is twofold. First, you want to have an easy way to distinguish (in the author's mind) how people of different cultures might behave or what they might look like. It makes our job easier to be able to say, for example, that if the two people who get mugged are a Yndan shadow-play actor and a Pesporri sailor, their reactions are going to be Foo and Bar, and their fighting styles and weapons are going to fit their culture. Second, we want to depict the Fantasy Counterpart Cultures as vivid, living, imperfect, and widely variable, because we don't want to make the FCCs into stereotypes. So yes, some people will claim that FCCs are unimaginative, especially if they are done badly. When they are done well, Guy Gavriel Kay wins another award. (I'm jesting just a bit, but in all seriousness, if you do a lot of writing with FCCs you should read The Lions of Al-Rassan, Tigana, or Under Heaven by Kay, and possibly Kushiel's Dart by Jacqueline Carey or The Lies of Locke Lamora by Scott Lynch. All of these authors do a great job of translating cultures that really existed into living-and-breathing fantasy versions, with some excellent worldbuilding thrown in.) I should warn you that if you're fairly new to using FCCs, you're probably better off keeping the "real-world" bits in the background. The more you borrow from the real-world culture, the more careful you have to be about making all the parts fit together, and the more research you'll have to do in order to satisfy readers. For example, ancient Egypt was extremely different from the Nubian or Bantu cultures, so if you create a matriarchal Black African civilization that still has pyramids in the background, I (as a reader) am going to balk. The pyramids represented enormous amounts of labor, supplies, wealth, and calories consumed, and would not have been constructed if the Egyptian religion were removed from the equation. A lesser danger is making the FCC people interchangeable. They need to have their individual quirks, beliefs, hobbies, and foibles just like any other character would. If every Yndan uses the same ujabi knife with an eight-inch blade when they fight, I'm not impressed. But if you show me a Yndan whose ujabi is small and silver and largely symbolic, who prefers to negotiate a peaceful solution instead of fighting, and who prefers to use their bare hands in combat because that lets them use more wrestling/joint-locking moves that won't kill the opponent, then I'm much more likely to see the Yndan culture as the varied, complicated, imperfect, wonderful thing that you envision, rather than a boring monolith. That said, the most important thing is to get your story written. If the characters come alive and the dangers they face are real, I won't bat an eyelash at a stray pyramid or two.
I think it's fine to take inspiration but try not to make things too similar to the real world or else it'll be rather boring. Instead mix and match cultures (but in ways that make sense.) and add in bits entirely of your own. Also remember that culture does not equal personality. This can be difficult and the main thing is to distinguish between things that someone would have a culturally taught reaction too, and things where they wouldn't. This is also especially true with evil cultures. It's not logical to be evil for the hell of it, so these evil civilizations will probably have a logical reason for being so. For example someone's culture might dictate that deformed children be killed at birth, which to us would seem barbaric, but it wouldn't mean they were horrible. From their point of view it would be merciful, and in a martial society they wouldn't be able to afford to have a week reed.
To quote TVTropes, "many Fantasy Counterpart Cultures are based on the theme park version of a particular region of the world". So basically, I feel that if you go somewhat deeper into understanding a particular culture and you describe it in enough detail and with enough sense of wonder and amazement any new culture deserves - it doesn't matter if you mixed it all up. And please, don't create "evil" societies. The concept makes sense only if perceived though the eyes of a xenophobic post-colonial Every society should show both sides of the coin. Some people are always going to feel oppressed - heretics, beggars, slaves, to name a few. And you are going to have all of them in every society. And then, most of the aristocracy is going to feel quite satisfied in just about any society that allows them to keep their wealth and status. Maybe the supreme ruler (emperor, shah, king, pope) is not quite himself, or he is under the influence of a rival party or he pays tributes to a barbarian king - again, he won't remain in power for to long without support of aristocracy or religious leaders.
When you create your little world, you have the ability to build a society the way you'd like to see a society. You have the chance to do things that won't be done on Earth. If there's some huge beast, then every city will have walls that have to hold it out. This is going to affect people in certain ways, depending on how much they can possibly travel outside the walls and such. So why do you go and take cultures that have already existed? The only excuse for this is when your world is actually Earth at a different point in time (i.e. The Dark Tower or pretty much anything by David Gemmell).
Never heard of Fantasy Counterpart Cultures before, but when I first started to think about my world, I was going to use different cultures as a base for theirs (which I still probably will... need to work soemthing out first). I don't see why you can or shouldn't use real-world cultures as a base for your fantasy-world, because personally, I think if they are distingushablely different then there is no problem.