Federal and state officials signed nearly 400 treaties with tribal nations in the 18th and 19th centuries. Threatened by genocidal violence, the tribes signed away much of their land. But they secured promises that they could continue to hunt, fish and gather wild food on the territory they were giving up. In 1836 a treaty was signed in which tribal nations ceded more than a third of the territory that would become Michigan in exchange for the right to hunt and fish on the land in perpetuity. An oil spill from the Line 5 pipeline would destroy the state’s ability to honor that right, Gov. Gretchen Whitmer said.