Here is an overview of the Larchmere Yys region of Hyperborea in my AS&SH campaign; the article is intended to represent information readily available to player characters.
Larchmere Yys, this small frontier region between the immense Spiral Array Mountains and the swampy Dagon Bay, was settled roughly half a century ago by Apollonian pilgrims. The people of Larchmere Yys Village (population c. 300) are a peaceful folk; they grow crops, herd goats, and continue the worshiping of Apollo to this day. The settlement is surrounded by strong larch timber walls, and watchmen are stationed in towers in the northwest and southeast; they are especially wary of strangers since people started to disappear without a trace.
To the southeast lies a deadly swamp known as the Toad Bog, infested with giant frogs and aquatic hydras. It is said the swamp is cursed and those who die here come back from the dead to feast upon the living. Just outside the swamp at the coast lies another village, Pisko (population c. 150). The seemingly welcoming inhabitants of this recluse settlement are in fact Dagonites, who have sacrificed many men who were unfortunate enough to set foot there. Allegedly, there are numerous underground tunnels connecting the major buildings to an ancient temple complex. The oldest of these tunnels might even lead down to the seabed where the fish-people and their aboleth masters live in their alien cities.
The hills to the south are presumed to be burial mounds of long forgotten kings. Further south lies a deserted wasteland, mostly inhabited by purple worms. The only notable site there is the Horrid Crater, where the infamous Witch of the Barrens lairs, whose prophetic powers are sought by many daring - and oft desperate - individuals.
To the west one finds the Spider Grove, a source of excellent timber in the region; also, giant spiders. Betwixt the forest and the great Lake of Mists stands a small community of all sorts of eccentric individuals; travellers, pilgrims, brigands, and hunstmen, these men of the road have finally found peace in their lives. Velmar (population c. 200) has an aura of unearthly languor as the inhabitants seemingly ignore the outside world and live only for the pleasures of the flesh.
To the northwest lies the Crystal Lake, whose waters are famous for their restorative powers. The lake is guarded by a vicious naga, who is known to be a collector of arcane curiosities. Further upriver stands the small Esquimaux village of Noatak (population c. 150). The people of Larchmere Yys have good trading relations with the Esquimaux; the ultimate goal is to convert them to the faith of Apollo.