The northern Border Forest is extremely rough country: wooded knife-edged ridges between ravines, with many small caverns and plentiful roaming monsters. In the northern forest, the plant monsters and prowling predators are fierce enough that even the hybsils don’t go there.
To the north of the Border Forest, the land continues to be “broken” and hard to traverse, with rocky badlands running right up into the frozen, wind-sculpted jagged ice of the permanently-frozen regions.
Mount Ghaethluntar is THE main flind realm that I know of, and they view the Zhents as a threat best fought in the gnoll lands
The Border Forest was once known as Rystall Wood by the Sylvan elves that lived there for many centuries after the Crown Wars. However, little evidence remains of their civilisation as they built few permanent structures. However in -4970 DR, Coronal Mhaenal of Rystall Wood was slain by monsters that were summoned into his bedchambers, ending the reign of the sixth Rysar in Rystall Wood.
In -5000 DR, Rystall Wood was cut off from the rest of Arcorar during the Twelve Nights of Fire that are started by a falling meteor. Rystall Wood becomes a separate forest and realm after the Twelve Nights of Fire clear away the mountain and hill trees that attached it to Arcorar. Although an independent forest after the event, its coronal still convened often with the leaders of the Elven Court.
- Hybsils roam the Border Forest in small tribes. They would be one of the threats/dangers to ZK caravans.
- Gnolls from Frozen Flindyke are also probably a big threat up there. Remember, these are the same flind-led gnolls whose shamans destroyed Northkeep and who may have been the shock troops of the Weeping War, so they are probably a big danger.
In 1372 DR the Border Forest is inhabited mostly by fey; due to heavy logging activities in the past, mostly from Snowmantle, the fey in this area tend to be more violent and hostile than in other parts of Faerûn.
Two Eldreth Veluuthra cells were known to be active in the forest around 1374 DR. One cell focused on raiding the Daggerdale border while the other concentrated on ambushing Zhentarim agents. The Eldrath Veluuthra in this area were supported by fey.
At the southern edges of the Border Forest lie the ruins of the Flaming Tower, once built by fire giants and destroyed by the Knights of Myth Drannor; the ruins are now inhabited by a powerful beholder, served by a force of goblins.