Much information is available on the Web, but one hundred times more is located inside archives. By telling some of the stories secreted in archives on your site, you will be bringing new knowledge to communities about their native history.
Tip on rivers: much discussion of native land in archives from the 16th to 19th centuries makes reference to rivers as the major landmarks. You may find it helpful to have before you a map of the rivers in your state, scroll down and enter your state name at this Maps of the World Site to do that.
Yale University has created a portal into primary source materials about Native Americans in the Northeast, here.