Before the collapse of Old Teral, there was a great and powerful elf-city called Gwydarliu, which men called Cathadria, within its borders. Though the Cathadrians resisted their conquest for many years, eventually they yielded to the Teralian general Archetor the Strider. These were the days before Teral's obsession with their mortuary cult reached its peak, and the elves were content to serve their distant master at Thalon.
In the years after Alanus the Fat's accession to the Imperial Throne of Teral, worship of the Necromancer began to spread. This was the time of the first Sworn Prince, Tywyn Lorianal of Gwydarliu. He pledged his service to Alanus, though the emperor was a reckless worshipper of the Necromancer Tharus. This began the long and awful decline of Cathadria, leading to its eventual depopulation when the Social War destroyed most of Teralian civil society.
Lorianal was succeeded by Oberys and Dorolien. Together, they have become known as the Sworn Princes. Their names are accursed for their complicity in the sins of Teral, never to be forgotten by the elves of Iiriem and the other nearby kingdoms for their crimes.
The Sworn Princes also ruled territory beyond the West Wall: a vassal-kingdom of elves called Seinaria, which means "beyond the wall" in Elvish. This kingdom was the retreat of the Sworn Princes. Though Lorianal is entombed beneath Cathadria itself, both Oberys and Dorolien were built great crypts in Seinaria, which now stands as a goblin-haunted ruin.
Myth and legend still surrounds the Sworn Princes as figures of great darkness: elves who sold the souls of their people for peace, security, and prosperity.