Plane of Isahnd
In the world of Isahnd, the scholars know they are hidden from other planes by the Glass Veil. The Veil was put in place by a powerful entity that the plane was named for, the great Isahnd, rumored to live in the Tower of No Doors. The residents are vigilant, whether they know why or not, to keep attempts of fiendish intrusion from manifesting. Each country has its own means, but they keep a watch to the lands to the north, where the constant hordes of orcs forway beyond the great rift valleys to harass the nations.