Between what two states does the valley the Ojibwe ceded their rights to by the Treaty of Old Crossing form the border?
Treaty of Old Crossing: By the Treaty of Old Crossing (1863) and the Treaty of Old Crossing (1864), the Pembina and Red Lake bands of the Ojibwe, then known as Chippewa Indians, purportedly ceded to the United States all of their rights to the Red River Valley. Red River Valley:  Forming the border between Minnesota and North Dakota when these territories were admitted as states in the United States, this fertile valley has been important to the economies of these states and to Manitoba, Canada.
Minnesota and North Dakota