In very old times the Lakota believed that there existed dangerous creatures called Unktehi. The Thunderbird, (Wakinyan) is said to be one of the Thunder Beings, a large bird-like creature who lives with Wakan Tanka (the Great Spirit) in the spirit world. The Thunderbird serves the Great Father by carrying messages from the earth to spirit world. One day the Unktehi and the Thunder Beings battled which caused the earth to shake and rumble till all the Unktehi died. Lakota consider the Badlands in South Dakota to be the place were Unktehi died and today we can see them in the fossil records.