Although some evidence exists of occupation during the Late Archaic period (around 1200 BCE) in and around the site, Cahokia as it is now defined was settled around 600 CE during the Late Woodland period.
 Mound building at this location began with the emergent Mississippian cultural period, about the 9th century CE.
The inhabitants left no written records beyond symbols on pottery, shell, copper, wood, and stone, but the elaborately planned community, woodhenge, mounds, and burials reveal a complex and sophisticated society.
 
The city's complex construction of earthen mounds required excavation, movement by hand using woven baskets, and construction involving 55 million cubic feet of earth, much of which was accomplished over a matter of just decades.
 Its highly planned ceremonial plazas sited around the mounds with homes for thousands connected by laid out pathways and courtyards suggest the location served as a central religious pilgrimage city.

The city's original name is unknown.
 The mounds were later named after the Cahokia tribe, a historic Illiniwek people living in the area when the first French explorers arrived in the 17th century.
As this was centuries after Cahokia was abandoned by its original inhabitants, the Cahokia tribe was not necessarily descended from the earlier Mississippian-era people.
Most likely, multiple indigenous ethnic groups settled in the Cahokia Mounds area during the time of the city's apex.

Historian Daniel Richter notes that the apex of the city occurred during the Medieval Warming Period.
This period appears to have fostered an agricultural revolution in upper North America, as the three-fold crops of maize, beans (legumes), and gourds (squash) were developed and adapted or bred to the temperate climates of the north from their origins in Mesoamerica.
Richter also notes that Cahokia's advanced development coincided with the development in the Southwest of the Chaco Canyon society, which also produced large-scale works in an apparent socially stratified society.
The decline of the city coincides with the Little Ice Age, although by then, the three-fold agriculture remained well-established throughout temperate North America.
Although some evidence exists of occupation during the Late Archaic period (around 1200 BCE) in and around the site, Cahokia as it is now defined was settled around 600 CE during the Late Woodland period.  Mound building at this location began with the emergent Mississippian cultural period, about the 9th century CE. The inhabitants left no written records beyond symbols on pottery, shell, copper, wood, and stone, but the elaborately planned community, woodhenge, mounds, and burials reveal a complex and sophisticated society.  
The city's complex construction of earthen mounds required excavation, movement by hand using woven baskets, and construction involving 55 million cubic feet of earth, much of which was accomplished over a matter of just decades.  Its highly planned ceremonial plazas sited around the mounds with homes for thousands connected by laid out pathways and courtyards suggest the location served as a central religious pilgrimage city. 
The city's original name is unknown.  The mounds were later named after the Cahokia tribe, a historic Illiniwek people living in the area when the first French explorers arrived in the 17th century. As this was centuries after Cahokia was abandoned by its original inhabitants, the Cahokia tribe was not necessarily descended from the earlier Mississippian-era people. Most likely, multiple indigenous ethnic groups settled in the Cahokia Mounds area during the time of the city's apex.
Historian Daniel Richter notes that the apex of the city occurred during the Medieval Warming Period. This period appears to have fostered an agricultural revolution in upper North America, as the three-fold crops of maize, beans (legumes), and gourds (squash) were developed and adapted or bred to the temperate climates of the north from their origins in Mesoamerica. Richter also notes that Cahokia's advanced development coincided with the development in the Southwest of the Chaco Canyon society, which also produced large-scale works in an apparent socially stratified society. The decline of the city coincides with the Little Ice Age, although by then, the three-fold agriculture remained well-established throughout temperate North America.
Cahokia