Gnomes are magical in my low-magic world not because they come from another plane, but because magic ages like a fine wine, and grows stronger over time. And it just so happens that thousands of years ago, a battle between cavemen-era humanoids (i'm thinking like, ten individuals at most) occurred inside a valley that the ancestors of Gnomes would eventually call home. During this battle, one of the combatants was able to (either in death or life, not sure). Enchant a primitive stone weapon into a basic +1 weapon. This weapon was used to kill an enemy on top of a rock, embedding the weapon into the stone while also cracking the weapon itself. This did nothing at first, but as the years went by and the weapon went untended, it's magic slowly grew more and more powerful, leaking out of the crack and slowly filling the valley.

In the present day, the Valley is known as the "feywild", and is filled with wild, primal magic. Anything that moved in there thousands of years ago has evolved into wild fey-like creatures such as the Gnomes. And anything that tries to get in today, is torn apart by the wild magic unless wearing a specialized suit. Gnomes and other Fey can leave the valley, but may require certain accommodations, such as regular inhalation of magic-laced air, and it may take training to get to that point. As a result of all of this, nothing moves into the feywild permanently, and very few ever leave it.


Not sure how strong that old stone weapon would be in the modern day. probably not even half as strong as it would have been if it hadn't been cracked.