Illinese

The Coureurs des Bois have but a very small settlement here; though at the same time it is not inconsiderable, as being the staple of all goods that they truck with the south and the west savages; for they can not avoid passing this way, when they go to the seats of the Illinese and the Oumamis, or to the Bay des Puans, and to the river of Mississippi.

1880, J. A. van Fleet, Old and New Mackinac, Grand Rapids, page 26

Of the several bands of the Illinese, who dwelt around the head of the lake and extended along the banks of the Illinois River, the country has long been destitute of a trace, except in those works of defence of a nomadic and predatory people which are still observed in tumuli, ditches, fortified cliffs, and inaccessible defiles which they were expert to occupy.

1884, Henry R. Schoolcraft, edited by Francis S. Drake, The Indian Tribes of the United States, volume 1, Philadelphia, page 313

It is not above half a league distant from the Illinese Lake, [Lake Michigan] an account of which, and, indeed, of all the other lakes, you may expect elsewhere.

1880, J. A. van Fleet, Old and New Mackinac, Grand Rapids, pages 25–26; translation of Baron of La Hontan, Voyages, (Please provide a date or year)

[…] the Illinese Country, and near the Missisipi^([sic]), the Venereal Distemper is very common.

1905, Baron of La Hontan, New Voyages to North-America, volume 2, page 465