The visit that the Sauk and Fox Indians made to Washington resulted in a new land cessation treaty.
The tan double triangle area was what was ceded. Poweshiek’s village was near Iowa City at the time–Poweshiek lived in that area for about 3-4 years.
This drawing of part of Johnson County shows where the treaty boundaries were.
This shows where Poweshiek’s village was.
This is Johnson County today.