Complex sentence: The Haudenosaunee Confederacy's use of modern weapons caused the wars to become deadlier, and historians consider the Beaver Wars to have been one of the bloodiest conflicts in the history of North America.
Split into simpler sentences: The Haudenosaunee Confederacy's use of modern weapons caused the wars to become deadlier. Historians consider the Beaver Wars to have been one of the bloodiest conflicts in the history of North America.