Although the return of Black Hawk's band worried U.S. officials, they were at the time more concerned about the possibility of a war among the Native American tribes in the region. Most accounts of the Black Hawk War focus on the conflict between Black Hawk and the United States, but historian John Hall argues that this overlooks the perspective of many Native American participants. According to Hall, "the Black Hawk War also involved an intertribal conflict that had smoldered for decades". Tribes along the Upper Mississippi had long fought for control of diminishing hunting grounds, and the Black Hawk War provided an opportunity for some Natives to resume a war that had nothing to do with Black Hawk.