history of - Why do the dwarves and elves hate each other?

In nearly every single medieval story Elves and Dwarves hate each other, or at least are very unfriendly towards each other. As I have read, watched and played many a lore of the medieval genre it just seems natural that Elves and Dwarves have a mistrust, at least, between them. (LOTR, Eragon, ect..)

I was just curious if there was a first lore that had created this or if there was some reason that it is? Or is it truly that Tolkien made it so for his lore in Lord of the Rings and due to it being one of the first and greatest, everyone else just followed suit?

(I do recognize that there is a question out there about this, but in it it is asking specifically about LOTR, I'm asking about outside of it and as the medieval genre in general. (Why don't Elves like Dwarves?)

Answer

This is a common genre trope.

Elves are tall and slender, Dwarves are short and stout. Making a physical difference like this is a common way to point out that the two groups are meant as a foil of one another.

Elves use swords and bows, weapons requiring flexibility and precision, representations of elegance. Elegance is power. Dwarves use axes, hammers and crossbows, which are primarily about direct (or in the case of the crossbow, mechanical) application of force. Strength is power.

Elves will focus on magic and spirituality and evince disdain for material things, or to be more interested in their elegance than their utility. Beauty is strength. Dwarves will focus on mining and smithing, sometimes use muskets or revolver-style pistols and various Steampunk machines and tanks, all representations of industrial, technological might. Innovation is strength.

Elves live in pristine woods, crystal spires or elegant palaces, emphasis on light and natural beauty, openness. Dwarves live in great halls and impregnable fortresses that are usually underground, emphasis on artifice and containment.

Elves are often portrayed as being masters of diplomacy, debate, rhetoric, Purple Prose, small talk and doubletalk. Dwarves are typically as straightforward as the grille of an oncoming semi.

Elves dress fancily, sing elaborate songs, write poetic literature in flowing script, and are embodiments of beauty and style. Dwarves are often unkempt, sport long beards and hair, and dress in either simple leather, undyed wool — or steel — and write prose in runes, carved into the rock.

Peoples (real or fictional) are often at odds when they come from such distinctly different backgrounds. Jimbo from southern Alabama is so culturally different from Sebastian from upper class NY City that it only makes sense for them to be at odds. But Jimbo and Sebastian can come together to fight aliens, much like:

The dwarf may gain a new respect for the elf's culture and deep learning, while the elf comes to appreciate the dwarf's craftsmanship and hard work. Also expect both sides to put aside their differences and team up against a third enemy, who's usually portrayed as primarily destructive (orcs, for example). The attribute shared by elves and dwarves primarily being creativity.