The Nightwood
Forest so dense and so old it has gone dark at midday, running along the Twilight Forest's far border. Bugbears hold it, along with a great many things that are not bugbears and have never been catalogued.
The Kingdom's maps mark the Nightwood as empty. That is the kind of error that comes from never sending anyone back a second time.
Geography
Unmapped in any useful sense. What surveys exist disagree with one another about the extent, and the 90 km² figure is a Leprechaun estimate made from altitude, at night, from outside.
Society
Bugbear society is spread thin and organized around sleep: they claim territory by dream-range rather than by ground, and a bugbear's holdings are the minds that fall asleep within reach. This makes their borders unmappable and their politics incomprehensible to outsiders.
It also means the Nightwood is the only region in the world where the ruling power knows what its subjects are afraid of, in detail, every night.
Relations
Quietly good with the Spriggans across the unmarked border. Formally uninvolved with the Great Hunt, which rides the Nightwood's edges and does not camp in it.