The Kirreskalds

From Introduction:

Where these curious creatures came from, no one can say for sure. They moved into their wintry mountain forests only a few centuries ago, but have guarded them zealously ever since. Outsiders are only allowed to enter their sacred valley when they come seeking prophecy, for the Kirreskalds are adept at the arts of divination. They do not sell these services cheap, however, and they also rob intruders before removing them from their lands. It is clear to their neighbours that they are avaricious collectors of various types of valuables, though what, exactly, they are after has remained a mystery.