So, Jewish Fantasy! A very nebulous idea that tries to catch form in many different ways. I don't know much about how it works outside of Israel - I saved the recommendation list that circulated around here but didn't try anything from it yet (outside of Spinning Silver, which I read before I ever saw the list). So, if anything of what I say seems ludicrous to you because you've seen a book that does it well - don't hesitate to recommend it to me! Though I'm not sure how applicable it will be for what I'm about to say.
There are a couple of angles from which one can try to get at Jewish Fantasy: through using Jewish folklore and myth as a basis for your story, through using Jewish characters or by writing out of a Jewish cultural context. In certain stories, different angles tend to be more pronounced - Charashta is based on Midrashim and Jewish folklore, Spinning Silver has Jewish characters, and Agam HaTzlalim is written out of some degree of Jewish culture. Yeah, two of those are Israeli books that weren't translated, feel free to give alternative examples but those are the only one I can safely talk about since I've actually read them.
I could elaborate more on that, but what actually made me want to write a post on the topic was a post about how so much of Fantasy is Greek (in a way) and Sci-Fi is Roman. And that made me think, what about Jewish Fantasy? And while this is a topic I've thought of and been somewhat involved in conversations on for some time now, this is looking at it from a particular angle. An angle which could be examplified by the simple question: why is there no Jewish Disney Princess?
All right, all right, settle down. I know about the Vanollope von Schweetz thing. Quite frankly, considering the source for it is the word of the actress and that it has no effect on the story whatsoever, I think I'm fine with ignoring it. Feel free to shout at me in the comments, hopefully the rest of the post will explain this better.
You see, the problem is that Disney Princesses mostly come from stories about Medieval Europe, and in that particular time and place "Jewish" and "royalty" were inherently contradictory. A Jewish girl couldn't have been a princess, because Jewish communities were never a part of the ruling class. At least not in medieval Europe.
Now the reason what I'm saying is rubbish is because of other contradictory examples, like Mulan or Tiana, and maybe Pocahontas or Esmeralda. And based off of those examples I could probably whip up a couple of ideas on how to do an interesting Jewish Princess story - base it on the Book of Judith, for example, or offer a Jewish twist on some European folktales (which might be hard considering some of them actually have straight up Jewish characters playing as the villains), or... have a movie about Jews assimilating into European culture... Yeah, I can see why Pocahontas or the Hunchback of Notre-Dame might feel a little uncomfortable. But the point is: Fantasy is based on Medieval times, and Jews' role during that time wasn't one of royalty.
You can't really write a medieval Jewish kingdom, because there wasn't really any. And yes, many people try using the Khazarians for that. However, their kingdom was only Jewish for a century, maybe, before it was completely destroyed. Plus, we barely have any data on what it looked like, and its culture was likely very different from Jewish culture. So the medieval presentation of Jews would have to be of a persecuted minority. That, essentially, is what we see in Spinning Silver: a Jewish family in medieval times, a member of which serves as our protagonist. And Maryem is pretty much constantly angry about the antisemitism flourishing all around her. So I suppose that could be an example to follow - along with the stories about Maharal of Prague and the Golem, fighting blood libels.
So, you can portray Jews as an oppressed minority, constantly fighting their persecution. An alternative could probably be following the example of Ḥassidic stories, talking about the Rebbe, the Renter, the Trader and the Widow (regular character archetypes in such tales). You could have the antagonist be the local Pariz, nobleman, or perhaps the gentile that decided to be a robber, or occasionally a fellow Jew who out-leassed your protagonist from their home. All regular tropes in the day-to-day life of an... (checks notes) early modern Eastern Europen Jew? Huh. I suppose it's not exactly the same period.
Either way, if you want your story to be more fuly Jewish, to not always play against the backdrop of a non-Jewish kingdom, you have some interesting options. The first question would be: are you taking from the past or the present? If you choose present, well, you can choose between Diasporan or Israeli culture. In addition, this will more or less constrain you to some type of Urban Fantasy or other Hidden World stories, with not much of an option to delve into Epic Fantasy. If that's what you want to do - great! Go ahead and do that. Personally, I have some degree of a problem with how I've seen Israeli culture portrayed in stories so far, but that's a story unto itself.
If you choose past... well... Jewish history is nothing if not long. And if we're really trying to make a more Jewish backdrop, we'll probably need to pull from Jewish independant states or kingdoms. Of which there are a couple that can be used - Ancient Israel throughout the time of the Tanach, from the Judges through the first kings and the divided kingdoms of Judea and Israel; Yehud Medinta, which while it existed under the Persians had a Jewish governor for certain periods; the Hasmonean Dynasty, with all its ups and downs; the Kingdom of Adiabene, which converted to Judaism for a time; some short-lived Jewish independant states in defiance of the Romans; and of course, the infamous Kingdom of Khazar. There are also legendary kingdoms of the lost 10 tribes, which could possibly work as interesting additions. It is also important to note that in the Tanachic period I included a pretty vast array of periods, including the Judges (periodical local saviors and heroes), the House of Sha'ul (which isn't too easy to characterize), the Davidic Dynasty (Temple! Prophets! A bloodline promised to last! Evrything you might want from a kingdom), and the Kingdom of Israel (a couple of dynasties have their own characteristics, but most didn't survive for long).
Maybe I'll try my hand in suggesting what a kingdom based on the Hasmonean Dynasty could look like later. For now, let us start with: there is no medieval Jewish kingdom, so we'll take one from the Hellenistic period or from the Bronze Age to cover it up! Either that, or we'll try figuring out the structure of the early medieval kingdom that converted to Judaism that one time.
I'm not sure how much of a point I made, really. Thank you for reading, and have a good day!
