Once upon a time, there was torrential rain. Such heavy downpour that the animals saw their homes flooding. They run to the hills, the flooding got worse; they run to higher hills, the flooding was still getting worse; eventually they couldn't help but gather together onto the largest hill of the region.

Such a ruckus wouldn't go unnoticed by the Mboi Guazú, the giant serpent; she woke up from her deep slumber, feeling a bit peckish. Unlike most animals she could see in the dark, and what she saw was a feast. Such abundance of prey! She could even ignore their meat, and go straight for the tastiest bits: the eyes.

So she ate the other animals' eyes. One by one. She ate so many eyes that they wouldn't fit the serpent's belly, but she kept eating them. So the eyes started appearing over her body, in-between her scales, creepily emitting light. The more eyes she ate, the more eyes she would have over her body, to the point that she was bright, she was light, she was fire.

She has become the Mboi-Tatá, or the "fire serpent". And she still roams those lands, looking for prey, burning the path as she goes through. If you ever find her while roaming, don't ever forget to close your eyes - and hope for the best.

Okay, that doesn't answer your question but I was in the mood of sharing a bit of the Guarani mythology, the fire serpent. This version of the myth is the one from the Mbyá.

If anyone wants I don't mind sharing other Guaraní myths. I also remember a few Kaingang ones.

Egyptian is pretty well-known but underrepresented in popular media.

There's a lot of weird Talmudic stuff about angels.

I once read a fairly interesting take on this: Historical settings are often chosen to wrap the story in a certain context in order to allow the reader to picture the style and theme without having to establish and explain a new setting first, so basically you skip on world building. If you read an analogy to Zeus you will immediately have an image in mind as well as a bunch of characteristics, no need to establish that beforehand.

Now, considering this it makes sense to choose a setting people already know - the 16th centruy Ottoman Empire is certainly interesting, but the average reader might know next to nothing about it and you have to explain everything first.

Why are these three settings used so much? Well, it's positive feedback! Literature, Theatres and Video Games will select something well known and it receives popularity. In addition, a piece of media using a less-popular setting will have to a) compete with other media to become popular and b) provide plenty of worldbuilding in order to have the setting make sense. A piece of media that both establishes a "new" setting AND is very popular is going to be rare, making the entry of a new mythology/historical setting into mainstream difficult.

I think there's at least 3 factors at play here.

First, you're probably living in a largely eurocentric bubble. You're not seeing other mythologies because they're not being marketed to you, and in some cases you may not even realize some of the ways that those mythologies and folklore and such are being presented to you because you just don't know what to look for (for example, Dragon Ball, in the beginning, borrowed very heavily from the 16th century Chinese novel Journey to the West, which is a hugely important book in Asian literature, and I swear every couple of years there's some new adaptation coming out, but it's not nearly as well known to Western audiences) and translations can get a little wonky, if you watch a movie or read a book from a non-western culture, instead of naming specific deities or other mythological figures, the translator may figure that no one reading the translation is going to know who that is so they'll translate it as something generic like "god" or "a great hero" instead of naming names.

Second, Western media is huge, and kind of overshadows a lot of other cultures. White Americans making movies in Hollywood are going to tend to pull from their own cultural backgrounds, and that often includes Greek, Norse, and Roman mythology.

Finally, a lot of it comes down to which mythologies we have actual written records of. The Norse, Greeks, and Romans all wrote about their gods to some extent, Slavic people, on the other hand, did not write until after they'd been converted to Christianity (the Cyrillic alphabet used in Russian and some other Slavic languages takes it's name from Saint Cyril, who helped to christianize the Slavic peoples, and was developed by his followers,) so there's no real first-hand accounts of their beliefs and practices, only second-hand accounts from other cultures who interacted with them and wrote down what they observed, and people recalling stories they'd heard about earlier times, and that comes with them inserting their own biases and interpretations and just plain getting things wrong. So if you wanted to write something about, for example, the Slavic gods Perun and Veles, you probably wouldn't have as much decent source material to work from as if you wanted to write about the roughly equivalent Norse gods- Thor and Loki.

cuz you live in the west ;) if you mean online, cuz it's made by the west

as a Hongkonger, almost all mythological references I see are Chinese

As many others are pointing out, cultural hegemony plays a major role—but I think there’s another factor at play as well:

Greek, Roman, and Norse mythology have been dead and fossilized for a thousand years and more, and in the meantime a long tradition grew up of mining them for allegory, with their prior religious significance stripped away. Most other world mythologies, on the other hand, still form part of active belief systems, or recently died out under colonial occupation and so carry postcolonial political overtones. So borrowing from them could be more problematical, whereas classical mythology has basically been left up for grabs by its former adherents.

Eurocentrism

In addition to the point about Western mythologies dominating because of cultural exports, I think there is also the undercurrent of England's original mythologies having been "lost" and so the English were always fascinated by the mythologies of the Norse (due to being invaded) and by the Greeks and Romans (as previous "great" civilizations they aspired to be).

Combine that with America's obvious English influences and the influence of England as a colonizer around the world, and those mythologies gained a huge outsized influence.

They are pretty fucking sweet

Because the west, which has been heavily influenced by these cultures, controls most of the media you consume.

I would like to see more Native American mythology.

It's like having kings or elves in a fantasy story. Readers know what to expect, so the writer doesn't need to establish that they're in charge, or that they're noble, etc. They're archetypes that most consumers are familiar with.

And writers stick to what they know. If they've been exposed to these mythologies, then they'll use them. If they're exposed to other mythologies, they'll use those.

Short answer: racism. Long answer, racism and colonialism.

Yes, it's definitely a problem. Folks are working on it. Lots of great new authors out there to read if you look hard enough. Ask your local librarian or bookseller for a hand finding stuff, they are great at this sort of thing. When I was looking for stuff for my kid a local bookstore turned me on to Rick Riordan Presents. The author of the Percy Jackson series made a publishing imprint that solely focuses on underrepresented mythologies and so far everything I've read from it has been great.

If you want something a bit more adult, Nnedi Okorafor has some really fantastic adult and YA novels that are based around Nigerian mythologies.

There's lots more out there, this is just what's at the top of my brain. I'll try to edit if I remember any other authors or series. I've been on more of a sci-fi kick lately so that's what's in my brain right now (ps go read Murderbot Diaries if you haven't already).

I'd say it's mostly racism and that many other polytheistic religions are still practiced. That's a political can of worms that western studios likely don't want to deal with.

Rule of Cool.

Spartans, Romans, Vikings.

I would love to see African, any Indengious, Central Asia, and Eastern Europe. What do all these mythologies have in common? They're not Anglo Saxon white.

The world was colonized by Western European countries who exported their preferred mythology.

Now, Greek, Roman, and Norse mythologies are now the default mythologies.

Obviously because western culture is the mainstream. There are a lot of movies/TV shows about, for instance, Korean culture. You just don't see them much because it's not mainstream. But thesedays, you can argue that they're getting pretty popular.

Enjoying and using one's own culture is clearly not racism. Not actively looking for different culture is not racism either; you can't force people to like something. And I think we're at a point where the general public is pretty much wide open to things from other cultures. Racist 4chan incels are definitely not the majority.

If something is good, it'll sell. Of course it's not that simple, but we do see more and more things from other cultures.

This is also why I never liked the idea of the black Little Mermaid. It's clearly just a virtue signaling Disney money grab that has nothing to do with black representation. If they could make money and look good by putting white power shit in their Snow White remake, they would. They just don't even try. If they really cared about representation, they should've come up with an actual African mythology story and not just put a black woman in a pre-existing story, as if Danish people at that time would've welcomed her like the movie. If anything, that's racist.

Good and authentic stuff sells. Surely it's not going to dominate overnight but just like how black music dominated(and still does) music industry, it'll get better over time with actually good representations.

I know that my argument oversimplifies a lot of things but it's doesn't help if you just say it's racism.

I can't speak for the people who brought this on, but I would guess it's a combination of how much they were adhered to as well as the complexity, uniqueness, and effectiveness of the narratives attached to them.

I think it’s often a western thing.