Complex sentence: Following another failed attempt in 1823, William H. Ashley and Andrew Henry began to establish operations on the upper Missouri River, an enterprise that would later be called the Rocky Mountain Fur Company, initiated the free trapping and rendezvous system.
Split into simpler sentences: Following another failed attempt in 1823, William H. Ashley and Andrew Henry began to establish operations on the upper Missouri River. The enterprise would later be called the Rocky Mountain Fur Company and initiated the free trapping and rendezvous system.