Worldbuilding is hard work. But you know what’s even harder than worldbuilding?
Doing it multiple times for a single story.
And yet, that’s what we see in many novels. While there are some that take place entirely in a single location, with a single culture present, quite a lot of them involve contact between different lands and different peoples. In some cases that contact is limited — characters from Country A traveling through Country B — but we also have situations where two or more cultures are jammed right up against each other for extended periods of time.
When this happens in real life, the result is cultures influencing one another, so that neither of them is left quite the same as it was before contact. This is a huge issue in the world today, thanks to the paired effects of colonialism and globalization; you can see that reflected via the recent upswing in novels that deal with empires and colonial control. That’s only one of the models by which culture contact can happen, but let’s look at it first.
When you have an outside power coming in, one of the first things you tend to see is a class stratification in people’s culture. The foreign elites behave in different ways — from clothing and cuisine to religion and ethical values — but that distinction almost never stays wholly confined to ethnic lines. Locals who can gain power by currying favor with the outsiders will also adopt those ways, with varying degrees of intensity and success. Around them you often get a penumbra of people who have picked up bits and pieces of the outside culture, e.g. wearing clothing that’s a medley of foreign and local elements. (That, of course, is assuming the outside power isn’t actively trying to impose their own ways on the indigenous population, which changes the slope of that graph quite radically.)
But the foreigners aren’t hermetically sealed away from their surroundings, either. The balance of power in this scenario certainly favors them, but again, there’s going to be a class difference between the elites who can afford to make everything exactly like it was at home, and their servants and laborers and soldiers and so forth, who perforce have to deal with the surrounding culture more regularly. Those people are (mostly) unlikely to change their religion or otherwise make a drastic shift, but they’ll acquire a taste for some of the local food, play some of the games, pick up stray words as slang, and so forth. Even the elites may find that they have to use local substitutes for certain things — especially where food is concerned, because importing perishables can be prohibitively expensive. They’ll still try to make the same kinds of dishes, but the ingredients will change. Materials for architecture and clothing also get swapped out, especially if they’re exports which would be considered expensive and desirable at homes.
Flip that around, and instead you have immigration: again a small foreign population surrounded by a larger local one, but with the power differential going the other way. Immigrant communities have to grapple every day with the tension between acculturating enough to the host society to find success there, and maintaining their traditional ways. They often have no choice but to use local materials, because they don’t have the wealth to import what they’re accustomed to from home, and they have to learn the local language if they want to get by (whereas a colonial power frequently relies on bilingual interpreters from the indigenous population). This scenario tends to be even more of a one-way street in terms of which culture influences the other, because the immigrant community is more isolated from their original context. They generally have only limited effects on the host society — in the U.S., restaurants serving that cuisine are a common example — while their own culture becomes a hybrid thing, distinct both from their home community and the one that surrounds them.
Now imagine that instead of populations directly interacting on a daily basis, suddenly Country A develops a fad for things related to Country B. You can see two versions of this sweeping Britain at different points in time, once with a living society (India) and once with a dead one (ancient Egypt). In that situation, instead of a lot of one community surrounding a small core of another, you get the material culture and concepts of one land being imported into the other as curiosities. Materials feature heavily in this scenario: perishables if they can be acquired (because great expense and therefore great prestige is involved), but also fabrics, animal skins and horns, exotic woods, and so on. Artifacts also get imported wholesale, in ways we’re still feeling the repercussions of today, with laws passed to protect indigenous patrimony and fights over the repatriation of museum showpieces. But you also get the more intangible import of artistic styles and decorative motifs, e.g. papyrus plants and lotus flowers suddenly sprouting in English parlours when Egypt became all the rage. There may also be a taste for the “occult mysteries” of the other country, as their foreign nature makes them seem more intriguing.
As you can imagine, though, there’s a lot of shrieking misrepresentation that goes along with this process. Egyptian hieroglyphics provide an excellent example: artists frequently glance at a few pictures, then proceed to draw real glyphs in nonsensical order, or even make up random “hieroglyphic” symbols of their own invention. The philosophical and theological underpinnings of those “occult mysteries” get discarded in favor of titillating spectacle, and artifacts get repurposed without any respect for their original context — which is especially bad when that original context was sacred. There’s certainly an influence on the importing culture, but it’s usually deeply insulting to any living members of the culture those things come from.
In a fourth scenario, instead of an imperial power, you have a crossroads or a port — some place that, thanks to travel and trade, gets different cultures passing through it on a regular basis. Places like this are fascinating, because of the complexity of what happens there. For the most part you’re getting only a limited slice of the populations not native to the area, like sailors and merchants, instead of a whole cross-section with families and all their associated activities. These groups may self-segregate to some extent, but they don’t wholly isolate; the whole point of being there is to trade with other communities. Being successful in a place like that often means speaking enough of several languages to get by, and knowing enough of the different customs to win favor and predict how the other guy’s going to act.
When it comes to the local population in a place like that, they’re going to be cosmopolitan. They’re not embracing the entire culture of a foreign land, but they will regularly make use of selected elements, creating a melange of multiple influences. And I don’t just mean material culture (though that, too); if the local religion is polytheistic, you’ll often find foreign gods developing their own cults or being co-opted into the existing pantheon. Meanwhile — and this happens with the “fad” model, too — the countries they trade with may well create versions of their exports tailored to the customers’ market, as happened in real history with Chinese porcelains made to suit European aesthetic tastes.
This is obviously just an extremely quick survey of some of the dynamics and effects we see in situations of culture contact. People have written entire books on each of the four scenarios I describe above; heck, there are entire academic fields which study such things. But I wanted to give this overview because authors don’t always see the factors that would be in play in such situations — and by that I particularly mean white authors, who tend to be more insulated from the dynamics of cultural influence than those from marginalized populations, i.e. people on the receiving end of that force. But if we put more than one culture into a novel, and it’s not just a matter of a character stopping briefly in a foreign town on their way to somewhere else, then we owe it to our readers to think about what would happen when those things smash into one another.