The Late Woodland peoples with their emphasis on small villages and hunting and gathering adaptation had previously occupied the Upper Mississippi Valley and Great Lakes Region prior to A.D. 1000.

In some areas, the Late Woodland population persisted until European contact, and even occasionally coexisted in the same time and place with the Upper Mississippians.

The Grand River, Lake Winnebago, Koshkonong, Green Bay (aka Mero Complex), Orr and Utz are Foci grouped under Oneota.

[2][8] Other artifacts that are diagnostic of the Upper Mississippian cultures specifically are double-pointed biface knives, long thin ovate blades, uniface humpbacked end scrapers, expanding base drills, sandstone abraders (aka "arrow shaft straighteners"), elk or bison scapula hoes, deer metatarsal beamers, pot sherd discs that seem to have been used as spindle whorls, and antler or bone cylinders that appear to be game pieces.

They may have been local Late Woodland populations who were influenced by the large-scale chiefdom entities; or they may have originated in one of these more advanced societies and set out to “colonize” the marginal areas to the north.

This may have been why the culture “reverted” back to a smaller scale society with lesser dependence on agriculture for subsistence, and more emphasis on hunting and gathering.

[13] The Upper Mississippian sites are mostly located on what is known as the Prairie Peninsula region of the American Midwest; including the states of Iowa, Missouri, Illinois, northern Indiana and southwestern Michigan.

These areas were ideally suited for the inhabitants to access resources in several different ecosystems; the prairie (bison, elk); river bottoms (nuts, berries, wild turkey), oak savannas (deer, elk, bear, wild berries) and the river itself with associated marshes and wetlands (fish, water lily tubers, mussels, turtles, waterfowl).

It was thought that the square houses found at the Zimmerman site may date to an earlier time period when growing seasons were more reliable and a settled agricultural life way led to construction of more substantial structures.

Later structures at the site were much more ephemeral, and may represent temporary wigwams at a time period when growing seasons were less reliable and the hunting of bison contributed more to subsistence.

The storage pits were thought to be constructed to help preserve food for extended periods of time; possibly through the winter, if the site is a permanent village.

[26][20] A large number of burials were excavated at the Anker Site which included exceptionally rich grave goods, implying they were wealthy or of higher status.

[23] In an excavation of human remains from both formal and informal burials at the site, 1402 disarticulated bones were uncovered, which would amount to anywhere from 84 and 92 people buried there.

[23] In excavations of human remains done in the central Illinois River Valley, which was an area of cultural interaction between the Upper and Middle Mississippian, many skeletons were partially decomposed before burial.

Therefore, efforts were focused on maize-beans-squash agriculture and hunting of large animals such as deer, elk and bison which provide significant amounts of meat to support larger populations.

[29] At sites where flotation techniques were used to recover small-scale plant remanis, the Eastern Agricultural Complex (EAC) of cultivated seeds such as goosefoot (Chenopodium berlandieri), little barley (Hordeum pusillum), knotweed (Polygonum) and sumpweed (Iva annua) are often present.

The tubers of American Lotus (Nelumbo lutea) and white water lily (Nymphaea tuberosa) have been recovered from roasting pits at some sites.

At the Schwerdt and Elam sites on the Kalamazoo River in southwestern Michigan, sturgeon bone and American Lotus tubers were found together in the same roasting pits; indicating a specialized seasonal encampment.

[21][10][32][33] The archaeological record often lacks evidence of daily activities because so much of the material culture is made of wood, fiber, plants and textiles that rarely survive for the archaeologist.

[citation needed] At any given Upper Mississippian site, on a daily basis the Native American inhabitants undertook a variety of tasks and activities.

Bone and antler projectile points and harpoons are additional hunting and fishing implements commonly found at Upper Mississippian as well as Late Woodland sites.

However, the same study found that the complex's inhabitants showed signs of childhood growth disruption and had deficiencies in fiber, calcium, folate, and Vitamin A, suggesting dietary issues.

[23] In addition, the inhabitants of Aztalan experienced a wide variety of health issues such as porotic hyperostosis, periosteal reaction, arthritis, as well as unspecified lesions.

In early Historic times, sometimes Jesuit rings have been found, indicating profession of Catholic faith as a result of French missionary activities.

[21][35] Works of art have been found at Upper Mississippian sites and it is probable that most of them were not looked upon simply for enjoyment or cultural appreciation, but for objects used by medicine men and/or to be used in ceremonies.

These include mask gorgets with artistic motifs, engraved pebbles, and animal or bird figurines made of bone, shell or copper.

Objects were thought to have magical qualities; using them in ceremonies would help to appease or get the support of deities or totem animals; and putting them in graves may assist the deceased into the afterlife.

Sometimes the bones of certain totem animals such as heron, bald eagle, crane, otter, or beaver were included in the grave, possibly as part of “medicine bundles”.

[2][1] Obsidian artifacts obtained at Upper Mississippian sites have been traced to volcanic sources in the Western Plains such as in modern day Wyoming and Idaho, and Southwest regions such as New Mexico.

[20][34][10] Upper Mississippian pottery usually comes in the form of globular, round-bottomed vessels commonly called “jars”, with restricted orifices and vertical to flared rim profiles.