Valley of the Wind is the east-most valley that runs parallel to Dry Camp Valley in the Ashlands. It leads up towards the Red Mountain, ending at the door to the Cavern of the Incarnate that only opens in the twilight. Two characteristic stone formations, called "Airan's Teeth," form the entrance into the valley. The Daedric ruin Zergonipal close by the mouth of the valley.
the eye of the needle lies in the teeth of the wind
the mouth of the cave lies in the skin of the pearl
the dream is the door and the star is the key.
By talking to different Ashlanders and Wise Women, the Nerevarine eventually finds out that the riddle points them to the Valley of the Wind, more precisely to the Cavern of the Incarnate, where Azura has hidden the ring Moon-and-Star.