This is my first post. I'm writing a fantasy novel, it is set in its own world. Is it acceptable to reference moral stories or fables from real history?
I suppose it could be made to work, depending on the rules you set up for your world. I would not do it, though. I would keep all references (historical, moral, literary, technological, etc.) within the world I'm writing about. As I've pointed out before, it would be ridiculous to mention a Harley-Davidson motorcycle in a story set in Tolkien's Middle-Earth. I wouldn't quote Shakespeare in a story set in the Star Wars universe (remember, it's a long time ago in a galaxy far, far away ...). Et cetera. I wouldn't mix my fantasy world with the real world. I wouldn't mix two different fantasy worlds (having Gandalf show up in an Iron Man movie would be weird). However, if the rules of your universe permit that kind of thing, and you can make it work convincingly, then go ahead.
you could also take the essence of moral stories or fables from real history and recreate them in your world.
You'd have to cloak them in your made-up world's history to keep them relevant. I've seen it done a lot. There are many fantasy milieu's that basically copy the history of one empire or another but redress it in the clothes of the fantasy world.