In the earliest days of this blog, I talked about my "fantasy manifesto", and part of it was, "Do Not Copy And Paste Cultures". I still believe in that fundamental idea, but the more I've thought about it, the more I think it's about Hard Imports and Soft Imports.
I mean, when building secondary world fantasy, you can't help bringing in certain elements from the real world. There has to be an anchor of some sort for the reader to get a hold of the fantasy world. The only question is, how much do you bring? And more specifically, how much do you bring from any one culture?
This is how I define things, roughly: if you bring a lot, give yourself plenty of well-known aspects for the reader to get a hold of, with recognizable titles and tropes-- in other words, copy-and-paste before you tweak it with your own elements, that's a Hard Import. If you bring only a bit, just enough to give it a familiar sense but not enough to feel like a full copy-and-paste, then that's a Soft Import.
The way I see it, the rule one should live by is this: You get ONE Hard Import. And your Hard Import should be your Viewpoint Culture.
Viewpoint Culture is, of course, the culture of your POV characters. And in fantasy, let's face it, 95% of the time, we're talking about some form of Medieval/Renaissance British/Western European culture. There are some variants-- Scott Lynch brings a certain Venetian flair to his, for example-- but that's typically what fantasists use. I'm not excepting myself either: the British elements* of Druthal are undeniably there, though I've also brought in elements that are distinctly American as well, and I hope that makes for something intriguing in the final mix.
The main point is, with your Hard Import, you're letting familiarity with real world elements and standard tropes do some of your heavy lifting, on the principle that you need a certain amount of heavy lifting done for you to get things moving. Someone once told me that "readers will allow you only one Big Idea"-- in other words, that you're world's basic set-up needs to be describable with a simple high-concept to define it.
So now we have the Soft Imports, and this is where you can really get yourself into trouble. Soft Imports are best where you can see what the influence is, but it's little more than influence. You read it and can say, "OK, this has a Middle Eastern flair" or "This has a Japanese flavor to it". But that's all. Those elements, again, give the reader some grounding of familiarity as building blocks for the worldbuilding that's going to dazzle them. But then you can take it that hint too far, that bit that's too much from our own world's equivalent culture, which will make them shake their head, and possibly even put the book down.
And it can be so little. It can be a single word. Jihad. Pharaoh. Samurai. Something that is too specific, and collapses your house of cards.
This also applies to Hard-and-Soft Imports from other fantasy works. Not to put too fine a point on it, but if you've got Elves and Dwarves and Orcs, well... everything else in your book better be very special.
*- One critiquer of the first chapter of an early draft of Holver Alley Crew commented, "I thought it was very British. Very, very British. As in, I'm shocked to learn you're not British."**
**- I did consume a lot of Monty Python and Douglas Adams in formative years, but even with that, I'm not sure what to make of that comment.