The Beaver Wars, also known as the Iroquois Wars or the French and Iroquois Wars, commonly refers to a series of conflicts fought in the mid-17th century in eastern North America. Encouraged and armed by their Dutch and English trading partners, the Iroquois sought to expand their territory and monopolize the fur trade and the trade between European markets and the tribes of the western Great Lakes region. The conflict pitted the nations of the Iroquois Confederation, led by the dominant Mohawk, against the French-backed and largely Algonquian-speaking tribes of the Great Lakes region.

The wars were brutal and are considered one of the bloodiest series of conflicts in the history of North America. As the Iroquois succeeded in the war and enlarged their territory, they realigned the tribal geography of North America, and destroyed several large tribal confederacies—including the Huron, Neutral, Erie, and Susquehannock—and pushed some eastern tribes west of the Mississippi River, or southward into the Carolinas. The Iroquois also controlled the Ohio Valley lands as hunting ground, from about 1670 onward, as far as can be determined from contemporary French (Jesuit) accounts. The Ohio Country and the Lower Peninsula of Michigan were virtually emptied of Native people as refugees fled westward to escape Iroquois warriors. (Much of this region was later repopulated by Native peoples nominally subjected to the Six Nations; see Mingo)