Isle of Frost

From Zelda Wiki.org

The Isle of Frost is an island that appears in Phantom Hourglass. The Island has two primary races of creatures on it: the Anouki and the Yook. Both were at peace with each other for 100 years, living on opposite sides of the island, until a Yook snuck into the Anouki village, and disguised itself as one of them. Link must resolve this conflict, and then get the Azurine from the Temple of Ice. After he clears the dungeon, it's revealed that the Yook were being mind-controlled by an evil force, and that they are actually quite friendly.