The Book of Kendring
You obtain this information from Finn:
There are many small family nests around the hills and foothills of the mountains. Some are isolated enough to be attacked on their own. However, they are very hard to find, as the smaller families move often. However, there are a couple of well-established concentrations of trolls within half a day’s travel of the Blue Starling stead.
Seventh Shadow sits on the lower slopes of Hordros Mountain. It has well-guarded approaches and near the edge of the treeline there is little cover for attackers to slip through. It is a great troll stronghold known for the Zorak Zorani berserks who defend it and occasionally foray down to the clan lands.
Seventh Shadow is the fortess of the Blood Shadows troll clan.
Curled Horn sits near a great blue rock massif in the Brambleberry Hills, above Dog-Rat Vale. The massif has the craggy shape of a face with a curving horn on its forehead.
The cliffs around here are dotted with many cave entrances, though the ones inhabited by trolls are hard to find, and there are many secret paths in and out. Great complexes of tunnels are said to be here, housing a large community of trolls. In the overgrown woods there is plenty of cover to be found for scouts or ambushers.
Curled Horn is the stronghold of the Following Dark troll clan.