The Bandit Queen is meant to be something of a marriage between Scottish Folklore and Norse Mythology (with my own twist, of course), though it has been primarily the latter that I've used for inspiration.
Norse Mythology: Alfar (elves), trolls, and dwarves are common elements of this mythology, and each of these at least gets a mention in the story. The chains wrapped around the Dechi to block their magic/strength are a reference to the story of Fenris Wolf. Many character names and place names are viking-esque. Odin (a Norse god) is associated with ravens and wolves, and Oliana is likened unto a raven, Dechar unto a wolf.
Scottish Folklore: Ghillie Dhu is the name of a faerie in this folklore, and most of Ghillie's traits are based off this very creature. But he's not 7 inches tall and doesn't die and get reborn every year. You're welcome. Also, my version has that scary dragging people underground with tree roots factor. The Boobrie, as described in Oliana's book that Keon buys her in Stromton, is the strict Scottish folklore interpretation of the creature. Those who have read know that I made significant upgrades to the coolness factor for this as it is depicted in the actual story.
The healing spring is something I believe to be associated with Norse Mythology, though the way I chose to describe this location in the story is very much a nod to the faerie pools in Scotland.