Complex sentence: The Indigenous peoples of the Great Basin are the Native American peoples of the Great Basin inhabited a cultural region between the Rocky Mountains and the Sierra Nevada, in what is now Nevada, and parts of Oregon, California, Idaho, Wyoming, and Utah.
Split into simpler sentences: The Indigenous peoples of the Great Basin are the Native American peoples of the Great Basin. The Great Basin is a cultural classification of indigenous peoples of the Americas and a cultural region located between the Rocky Mountains and the Sierra Nevada, in what is now Nevada, and parts of Oregon, California, Idaho, Wyoming, and Utah.