She is the guardian spirit of the Dál gCais, the Dalcassians or Ó Bríen clan. She was the ruler of a sídhe in north Munster, and her dwelling place was Craig Liath, the grey rock. She also has a magic harp of which it was said "whoever heard its music did not live long afterwards". She is believed to be a daughter of the Cailleach and was turned into a white cat by her sister, Clíodhna.