The basis for the Black Hawk War stems from the treaty of 1804, the first treaty between the United States government and the Sauk and Mesquakie natives. This treaty obliged the natives to cede all their land east of the Mississippi River for a very small price. Black Hawk refused to honour the treaty, arguing American officials did not consult with all the Sauk and Mesquakie council leaders. Furthermore, the natives who signed the treaty were intoxicated with whisky.

In 1816, the Americans imposed another treaty on the Sauk and Mesquakie nations. This treaty was meant to reaffirm the treaty of 1804 and clarify the misunderstandings that might have given the natives any right over the territory. Black Hawk reluctantly signed this treaty, but still felt the land belonged to him and his people.

In the 1804 treaty, Article 7 states, "As long as the lands, which are now ceded to the United States, remain their property, the Indians belonging to the said tribes, shall enjoy the privilege of living and hunting upon them." The Americans honoured this article until 1828, at which point white settlers began encroaching on Sauk and Mesquakie territory. The government then called for the removal of all natives living east of the Mississippi.

In 1831, war was on the verge of breaking out. The Articles of Agreement and Capitulation were created, discrediting Black Hawk's authority. According to this agreement, which became known as The Corn Treaty, Black Hawk had to accept the authority of Keokuk, return to the west of the Mississippi, and sever all ties with the British. In return, Black Hawk's band was to receive the same amount of corn they would normally get from their abandoned cornfields. The U.S. government never provided the right amount of corn. As a result, many natives suffered from starvation, and their mistrust of the white people grew.

On September 21, 1832, following the Black Hawk War, Keokuk signed the peace treaty. This treaty forced the Sauk and Mesquakie to relinquish another 2.5 million hectares (6 million acres), and forfeit the right to plant, hunt, or fish on the land ceded as per the treaty of 1804. The natives were to receive $600,000 over a 30-year period. The land was really worth much more than this.

As non-native settlement was rapidly expanding, the U.S. government set their sights on the land west of the Mississippi, land belonging to the Sauk and Mesquakie. By 1836, 10,000 non-natives settled in that area. Keokuk wanted to avoid confrontation and sell the land to the government. The treaty of 1836 was signed with the natives agreeing to let go the bulk of their land.

One year later, Keokuk signed the Second Black Hawk Purchase. In this land cessation Keokuk gained a great deal of personal wealth. More land was lost in 1842 when the tribes signed away four million hectares (ten million acres) in Iowa to cover mounting debts.

Today, the U.S. officially recognizes three Sac and Fox Tribes: the 1100-member Sac and Fox Tribe of the Mississippi currently living on 453 acres of land in Kansas, the 400-member Sac and Fox Tribe of Missouri now living on 3200 acres of land in Iowa, and the 2200-member Sac and Fox Tribe of Indians of Oklahoma with 1000 acres of land.