There is a book called 1491, which discusses the Americas pre-Columbus. It started with what is now modern day Mexico, and unfortunately I had to return it to the library before getting much farther in. But I bet that the later chapters would cover the American West which would include that area. At least for the creation myths portion of your question.
mullaloo t1_iyylqlf wrote
Reply to How did Native American tribes indigenous to Yellowstone National Park (e.g., Shoshone, Blackfeet, Crow, etc.) perceive the land (e.g., thoughts on geothermal activity) and what was their relationship like with white/European trappers and explorers entering the region in the early 1800s? by electricdresses
There is a book called 1491, which discusses the Americas pre-Columbus. It started with what is now modern day Mexico, and unfortunately I had to return it to the library before getting much farther in. But I bet that the later chapters would cover the American West which would include that area. At least for the creation myths portion of your question.