Complex sentence: Pierre's Hole, a shallow valley in Idaho, USA west of the Teton Range that collects the headwaters of the Teton River, it was a strategic center of the fur trade of the northern Rocky Mountains.
Split into simpler sentences: Pierre's Hole is a shallow valley in Idaho, USA, west of the Teton Range, that collects the headwaters of the Teton River. It was a strategic center of the fur trade of the northern Rocky Mountains.