Complex sentence: The vast wealth in the fur trade created enforcement problems for the monopoly whereby unlicensed independent traders, known as "coureurs des bois" (or "runners of the woods"), appeared in the late 17th and early 18th centuries.
Split into simpler sentences: The vast wealth in the fur trade created enforcement problems for the monopoly. Unlicensed independent traders, known as "coureurs des bois" (or "runners of the woods"), began to do business in the late 17th and early 18th centuries.