The Illinois Confederation, also referred to as the Illiniwek or Illini, were made up of a loosely organized group of 12 to 13 tribes who lived in the Mississippi River Valley.

Eventually member tribes occupied an area reaching from Lake Michicigao (Michigan) to Iowa, Illinois, Missouri, and Arkansas.

[10][11] The tribes are estimated to have had tens of thousands of members, before the advancement of European contact in the 17th century that inhibited their growth and resulted in a marked decline in population.

While the men usually hunted, traded, or participated in war, the women cultivated and processed their crops, created tools and clothing from game, and preserved food in various ways for storage and travel.

In 1851, an Indian agent reported that the Peoria and the Kaskaskia, along with their allies, had intermarried among themselves and among white people to such an extent that they had practically lost their tribal identities.

The treaty also provided for opening the Peoria-Kaskaskia and the Wea-Piankashaw reserves in Kansas to settlement by non-Indians[16] Eventually, the remnants of these tribal groups reorganized under the name of the Confederated Peoria.

Jacques Marquette, a French Jesuit missionary, claimed that Illinois was derived from Illini in their Algonquian language, meaning 'the men'.

These tribes are the Kaskaskia, Cahokia, Peoria, Tamaroa, Moingwena, Michigamea, Chepoussa, Chinkoa, Coiracoentanon, Espeminkia, Maroa, and Tapouara.

[23] It is thought that when the French first encountered the Illiniwek tribes, there were as many as 10,000 members living in a vast area stretching from Lake Michigan out to the heart of Iowa and as far south as Arkansas.

[21] Before long, however, Eurasian infectious diseases and the ongoing Beaver Wars brought high mortality to the Illiniwek, causing their population to plummet over the coming decades.

[24][failed verification] The early French explorers, including Louis Jolliet, Jacques Marquette and René-Robert Cavelier, Sieur de La Salle, produced accounts that documented the first discovery of the Illinois.

The wars had arisen due to the conflicts between tribes for resources and trade goods, or were initiated by European explorers looking to expand their land.

[15][23] Some of the Illinois people's prominent enemies were the Lakota (Sioux), Osage, Pawnee, Sac and Fox Nation and Arikara to the west and the Quapaw, Shawnee, and Chickasaw to the south.

[27] The Iroquois, hoping to replace deceased kin through adoption and looking for new hunting grounds after exhausting their own resources, killed or captured many Illinois people through their war parties.

[19] Pushed out by the Iroquois and Shawnee and facing more numerous European settlers, the Illinois accepted a reservation in 1832 at the Big Muddy River south of Kaskaskia.

[23] In 1867, they resettled in a new reservation in Northeast Oklahoma and were eventually joined by members of the Miami Tribe, who became an official part of their new confederation in 1873.

[17] Growing bountiful produce, raising many children, and being a faithful wife were signs that led to an elevated status as well as respect among the natives.

[26][17] While a great portion of the tribes eventually converted, some tribal elders rejected the religions and worked to retain their beliefs in the spirit world.

[34] The Illinois men and women practiced dream seeking, a ritual in which young boys and girls of about fifteen years of age would paint their face and isolate themselves to fast and pray as a means to reveal to them a specific spirit guardian upon which they would depend on to guide them for the rest of their lives.

[31] Maize was the primary crop, but the Illinois also planted beans, squash, pumpkins, and watermelons, and gathered wild foods in the forests.

Maize was planted in late spring and harvested prematurely in July, at which point most was preserved in order to prepare for the coming winter.

When in close proximity, the hunters would shoot their arrows and spears and force the animal in the opposite direction, towards the rest of the hunting party.

In the course of their yearly activities, the Illinois people produced virtually all of the foodstuffs and other material products they needed to maintain their way of life.

[38] As time passed, traders and missionaries began to settle among the Illinois and their formerly self-sufficient economy became increasingly dependent upon their French allies.

[33] Direct political leadership was established and maintained by peace chiefs, who were in charge of organizing communal hunting expeditions and communicating with leaders of other tribes.

[21][26] These roles were not inherited, but could be achieved through a demonstration of great battle skills, as well as through convincing the other warriors that his manitou could guide them into a successful raid.

[24] For those who died in the battle, it was the war chief's role to compensate the families of the deceased through gifts and lead another raid against those who killed the warrior as a means to enact vengeance.

[14] Though chiefs had the authority of political power and were widely respected by the people, the egalitarian society of the Illinois presented a more democratic environment in which important decisions that effected the community were made by tribal consensus.

It was only through the expansion of European ideals and direct contact with French officials that influenced the chiefs to wield greater power over their people.