Fairy-Struck
The kingdoms were in the same realm but on different continents so the Fey used the paths to travel between them.
The Fairy Realm itself was layered over our world, and I'd been told America was somewhere between the courts; with the Seelie Kingdom laid over Europe and the Unseelie over Asia. Of course, it's not precise, but the fairy mounds of Europe lead to the Seelie Kingdom and those in Asia lead to the Unseelie so we just made the assumption. We'd known there were fairy mounds in America, but no human had ever been allowed through one, and we hadn't known where they connected to in Fairy. Now, I knew why; they led to the secret Twilight Kingdom.