Indian Reservation

In 1957, I went on vacation with my parents and grandparents to Backus. I learned to swim on the lake that our cabin was on and was taught by a group of little Indian boys. We were told that they were from the local reservation. Is there still a reservation in the area ? Any idea what tribe these Indians could have been from? I am thinking about a return trip to Hackensack, Backus and Bemidji area and would like to learn more of the local Native Americans of the 1957 era. Thank you for any help you can give me.