Complex sentence: Native Americans found that Cheyenne Mountain was a good source of wood for teepee poles, and was visited by Cheyenne and Arapaho people, who may have sought spiritual inspiration from the mountain's waterfalls.
Split into simpler sentences: Native Americans found that Cheyenne Mountain was a good source of wood for teepee poles. It was visited by Cheyenee and Arapaho people, who may have sought spiritual inspiration from the mountain's waterfalls.