To each faction Thrana encounters, its diplomats give a map of North America to prove its wisdom. Using geographical features and places devoid of civilization as boundaries, the map divides the land into sectors which, they say, are practically the only land worth paying attention to for each of the factions in said sectors.
One of the sectors is known as Garthanum. East to West, it expands from the peaks of the Appalachian mountains to the Atlantic Coast, encompassing the broadest part of the Chesapeake Bay. North to South, it is centered around the James River watershed, with borders at the Roanoke and the Rappahannock. It includes the ruined human cities of Norfolk, Chesapeake, and Richmond, among other myriad towns and farms and dilapidated roads.
Yet there is bustling civilization amongst the wreckage; Garthanum has consistently been one of the most densely populated areas as recorded in the Thranau National Ground Settlement Survey. Indeed, the squabbling little clumps of society have settled their differences with greater speed than anywhere else, for various reasons. Naturally, this is mildly concerning to the Thranau. A great power lurks beneath the trees here, a power that, alone of all things in the world, shakes their utopian vision to its core.
But enough dreary exposition; on with the show!