Complex sentence: The trade route on which Thistle lies was used by Native American tribes before the arrival of European settlers; two Ute Indian chiefs, Taby and Peteetneet, led seasonal migrations through the canyon each spring and fall.
Split into simpler sentences: The trade route where Thistle lies had been used by Native American tribes prior to the arrival of European settlers to the area. Two Ute Indian chiefs, Taby and Peteetneet, were known to lead seasonal migrations through the canyon each spring and fall.