<P> The Illinois Confederation, sometimes referred to as the Illiniwek or Illini, was a group of 12--13 Native American tribes in the upper Mississippi River valley of North America . The tribes were the Kaskaskia, Cahokia, Peoria, Tamaroa, Moingwena, Michigamea, Chepoussa, Chinkoa, Coiracoentanon, Espeminkia, Maroa, and Tapouara . At the time of European contact in the 17th century, they were believed to number over 10,000 people . Most of the Illinois spoke various dialects of the Miami - Illinois language, one of the Algonquian languages family, with the known exception of the Siouan - speaking Michigamea . They occupied a broad inverted triangle from modern - day Iowa to near the shores of Lake Michigan in modern Chicago south to modern Arkansas . By the mid-18th century, only five principal tribes remained: the Cahokia, Kaskaskia, Michigamea, Peoria, and Tamaroa . </P> <P> The Illinois River (Inoka Siipiiwi) (" the River of the Inoka, i.e. Illinois") and the entire vast Illinois Country are named after the Illinois Confederacy . </P>

What native american tribe inhabited what is now chicago