According to the United States, the leaders of the Sac and Fox groups "signed" a treaty in 1804 which deeded the land west of the Fox River to the US. Black Hawk did not acknowledge this treaty because the negotiator, General William Henry Harrison, did not consult the entire council of Sac and Fox nations.

Before 1700, the Potawatomi lived in the upper Great Lakes region. During the 18th century however, they were forced south from their homes by invading Iroquois war parties. The Iroquois battled for hunting rights and the Potawatomi were not numerous enough to fight back.

Many different groups migrated in and out of the Northern Illinois region from the time of Columbus (1492) to the white settlement of the Fox River valley (1833). Most of the groups were Algonquin-speaking people and included the Sauk, Fox, Illiniwek, Kickapoos, Miamis, Potawatomi, Menominee, and Winnebago.

Present day prehistoric archaeologists take part in heated debates over the peopling of North America. The most widely regarded theory is that people migrated over the now non-existent land bridge between Russia and Alaska and trickled down the coast of North and South America, gradually moving inward. The people are estimated to have started populating the Americas either 30,000 years ago or 12,000 years ago.