The Illinois Confederacy, originally known as the Illini Confederacy, was a confederacy of Algonquian tribes made up of the Kaskaskia, Peoria, Michigamea, Moingwena, Tamaroa and Cahokia tribes.

Later, as the tribal populations were decimated by wars and epidemic illnesses, at various times some of the tribes combined and recombined into mixed nations:

The Cahokia united with the Tamaroa. 
The Tamaroa united with the Peoria.
The Peoria united with the Kaskaskia. 
The Michigamea united the Kaskaskia.
The Pepikokia united with the Wea and Pinkashaw.
The Wea and Piankashaw united with the Peoria and Kaskaskia.

Other smaller affilliated groups were the Taporouas, the Moingwenas, the Chinkoa, the Omouahoa, the Coiraconetanon, and the Chepoussa, While some authors (e.g., Scott) consider the Wea (Ouiatenon) and Piankeshaw to be Illinois affilliates, in fact these two well-known tribes are members of the Miami family, which eventually became part of the Western Confederacy.

The Miami and Illini did speak a mutually intelligible language, albeit with dialectical differences. Early French commentators believed that the Illini and Miami came from a common ancestral tribe that split in the late prehistoric period. When the French arrived in the Seventeenth Century, the Illini and Miami appear to have become two distinct tribal families.

The basis for the Illini Confederation of tribes appears to have been common historical roots, clan and kinship ties, and cultural commonality. Hauser argues effectively that once the Illini were in fact a single tribe; that they split into sub-tribes when their population became too large for successful hunting and subsistence agriculture. He further argues that the constituent sub-tribes maintained a strong identification as being Illini. Even after the split, there was a single chief of the Illinois as well as numerous sub-chiefs among the sub-tribes. Jolliet spoke of meeting an Illinois village chief (in Iowa) and subsequently being conducted to Peoria to meet the "Grand Captain" of all the Illinois. Thus, it appears there was a central unifying authority figure among the Illini.

Illinois Territory

The Illinois country reached the Illinois-Wisconsin border to the north. The French in fact named Lake Michigan as "Lac du Illinois" or Lake of the Illinois because of the proximity of the Illini. Their territory stretched eastward to the Wabash River basin and extended westward across the Mississippi River into eastern Iowa. The Illini treated the Ohio River as their southern territorial boundary, although there is anecdotal evidence that on occasion, they hunted in what is now northwestern Kentucky. That country was claimed by the Chickasaws, a nation of fearsome warriors alligned with the British and utterly opposed to the French.

For a time, the Michigamea (also "Mitchigamea") subdivision established themselves on the St. Francis River in northeastern Arkansas. This placed them near the Quapaws whom they aided in their fight against the Chickasaws. They later relocated to the vicinity of Fort De Chartres, located in what is now Randolph County, Illinois, in the early 1700s.

Some suggest that the Michigamea were late-comers to the confederation; that the Illini "adopted" the tribe in late pre-historic times. Others such as Hauser contend that the Michigamea were part of the original Illini root stock; that their journey across the Mississippi happened for the same reasons that caused the other sub-tribes to often leave the Illinois River valley.

Such reasons might have been better hunting to the west, traditional migratory patterns, and pressure from the Iroquois to the east and the Sioux to the north. With that possible exception, the Illini range, then, can be said to include all of the present state of Illinois, and the lands immediately adjacent to that state. However, during their hunting and wars, the Illini traveled far beyond this region on many occasions.

KASKASKIA ("Kaskaskahamwa")

In 1673 the principal town of the Kaskaskia tribe was near the present site of Utica, La Salle County, Illinois. In 1700 they moved to the mouth of the Kaskaskia River, located in present day Randolph County, Illinois. In 1769 an incident in Cahokia, Illinois between a Kaskaskia warrior and the great Ottawa chief, Pontiac resulted in the death of the chief. Tribes from the north (Sauk, Fox, Kickapoo and Potawatomi) swore vengeance and began a war to exterminate the tribe.

The Kaskaskias were parties to at least fifteen treaties with the United States. Under the terms of a treaty made at Vincennes, Indiana on August 30,  1803, the Kaskaskias ceded all of their claims to land in the Illinois Territory in return for the care and protection of the United States "against other Indian tribes." In 1832 they, along with the Peoria's, were assigned 150 sections of Kansas lands, and they have since been identified as part of the Peoria tribe.

PEORIA

Formerly one of the principal tribes of the Illinois Confederacy belonging to the Algonquian linguistic family, the Peoria got their present day name from the French from "Peouarea," which was actually the name of a particular person meaning  "he comes carrying a pack on his back." 

Historically they lived near the mouth of the Wisconsin River in the general region of Prairie du Chien, Wisconsin. In 1670, the Peoria were moving southward from the Wisconsin River. Three years later a tribal band living near the Moingwena at the mouth of the Des Moines River moved over to the east side of the Mississippi in the vicinity of present day Peoria, Illinois. Towards the later part of the seventeenth century, some bands lived southward on the Mississippi in present day Illinois and Iowa.

Their enemies, including the Kickapoo and the Fox, began a war of extermination against the tribes in Illinois, after the French and Indian War. A part of the Peoria with some of the Wea settled on the Blackwater Fork near St. Genevieve, Missouri. The main part of the Peoria remained on the Illinois River.

From their first treaty with the United States in 1818, the Peoria were united with the Kaskaskia. In 1832, the treaty resulted in the remnants of five tribes of the Illinois Confederacy giving up their land claims in Illinois and Missouri to the United States. A tract of 150 sections on the Osage River was assigned to the Peoria and the Kaskaskia, extending east from the Wea and Piankashaw reserve in present Miami County, Kansas. Here the Peoria prospered under the influence of the Roman Catholic mission.

In 1849, the great influx of white settlers soon saw the Peoria and Kaskaskia joining their neighbors, the Wea and Piankashaw, to form a confederated tribe for mutual benefit and welfare. This confederation also included the last remnants of the Chaokia, Moingwena, Michigamea and Tamaroa, who had become a part of the Peoria many year before, as well as the Pepikokia, who had joined the Wea and Piankashaw in the later part of the eighteenth century.

An 1851 Indian agent reported the Peoria and Kaskaskia and allied tribes had practically lost their identity through intermarriage among themselves and with white people. A 1854 treaty officially recognized this union of tribes, referred to as the Confederated Peoria. The treaty provided for the opening of the Peoria-Kaskaskia and the Wea-Piankashaw reservations.

The organization of the state of Kansas in 1861 found the Indian tribes being harassed by illegal taxation of their property and inequalities under the state laws. Many of the Indians lost their individual land holdings within a few years. The government pushed its plan to remove all the Indian tribes from Kansas to the Indian Territory by the close of the Civil War. 

The Omnibus Treaty, filled with complicated terms which named ten tribes in Kansas was signed at Washington on February 23, 1867.

The new reservation of 72,000 acres lay west and south of the Quapaw in present Ottawa County, the land having been purchased partly from the Quapaw and partly from the Seneca and Shawnee. Fifty-five Peoria remained in Kansas to become citizens of that state.

In 1873, Congress enacted a law providing for the union of the Miami of Kansas with the Confederated Peoria, under the title of United Peoria and Miami. However, the Miami declined this union and remained a separate tribe. Members of this united group were predominately of mixed-blood Indian and white descent. 

The Peoria and Miami lands in Oklahoma were allotted in 1893, and the excess given to Ottawa County in 1907. By the 1930s both the Oklahoma and Indiana Miami were completely landless, although the Oklahoma tribe has since acquired 160 acres which are held in trust. The United Peoria were terminated in 1950 but restored to federal status in 1972. The Miami Tribe of Oklahoma never lost its federal recognition, something the Indiana Miami have never been able to regain.Today, the Peoria are known as the Peoria Tribe of Indians of Oklahoma and the Miami are a separate tribe called the Miami Tribe of Oklahoma.

MICHIGAMEA

Michigamea, which Lake Michigan is named after, is said to be derived from Mishigamaw, "the great water" or "big lake."

The Michigamea's original home was near the headwaters of the Sangomon River in Illinois. Under pressure of enemies from the north, including the Sioux, the Michigamea migrated at an early date from Illinois to a large lake in what is now northeastern Arkansas, where they were found by Marquette in 1673.

About 1700 they were driven from this region by their enemies, among whom were the Chickasaw, and returned to Illinois. They soon joined the Kaskaskia with whom they later identified in history.

Descendants of the Michigamea can be found among the Peoria Tribe of Indians of Oklahoma.

MOINGWENA

The name Moingwena or Moins was applied to this tribe by the French from the name of their village, Moingona, meaning "at the road." This is thought to reference the well-known Indian trail leading from the head of the lower rapids to the village of Moingona at the mouth of the Des Moines River, near the present town of Montrose, Lee County, Iowa.

Marquette in 1673 reported the Moingwena,  living on the west side of the Mississippi Rover near the Peoria, in the Des Moines River region. Afterward the Moingwena lost their tribal identity and became a part of the Confederated Peoria whose descendants can be found living in Ottawa County, Oklahoma, now known as  Peoria Tribe of Indians of Oklahoma.

Tamaroa

The name Tamaroa is said to be from the Illinois word tamarowa, meaning "cut tail," which was a reference to a totemic animal, perhaps the bear or the wildcat.

In 1680 the Tamaroa lived on both sides of the Mississippi River at the mouths of the Illinois and the Missouri rivers. Their friendship with the French made the Chickasaw and the Shawnee their enemies, and both tribes waged a continual war on the Tamaroa. 

Two Tamaroa leaders signed the treaty of 1818 by which the Illinois tribes, including the Peoria, ceded approximately half of the present state of Illinois to the United States. The name of the Tamaroa is listed in the treaty made with the Kaskaskia and the Peoria at Castor Hill, St. Louis County, Missouri on October 27, 1832. With these treaties, the Tamaroa became a part of the Peoria and descendants may be found in Ottawa County, Oklahoma.

CAHOKIA

The Cahokia were one of the leading tribes in the Illinois Confederacy in the early 1700's and were living near the site of present Cahokia, Illinois. They were closely associated with the Tamaroa. The name of the tribe was given to the largest prehistoric artificial earth mound in the United States, located about six miles east of St. Louis, Missouri in Madison County, Illinois.

At the 1818 Treaty of Edwardsville (Illinois), five of the Cahokia chiefs and head men joined others of the Illinois Confederacy tribes in ceding to the United States half of the state of Illinois.  Henceforth, the Cahokia became part of the Kaskaskia and Peoria tribes, and today their descendants may be found in Ottawa County, Oklahoma.