During the peak of the hostilities between the Arcanians and the Terethians, the realm of Old Terethia was invaded. When the forces of humanity reached the Twilight Bastion, they were stunned to find it abandoned. The guenvae who dwelt there had disappeared, leaving almost everything behind. The Twilight Bastion was raided and many of the Old Terethian spellbooks, records, and artifacts were transported to Arcania.
It is now known what became of the Terethians of the Twilight Bastion. Some theorize that interworld travel had been attempted. But whether this was successful could only be speculated.