Cahokia and the Mississippi Mound Builders
Phases of Cahokia

Although there is ongoing debate about the dates for these periods and the need to continue refining them, following is a summary of the current thought on the four phases of Cahokia.

The Lohmann Phase (A.D. 1000/1050 to 1050/1100)
This phase saw the appearance of town and mound centers.  The first layer of Monks Mound, the largest and most central mound in Cahokia, was begun during this period.  This was a time of political, religious, and social transformation from that of the Emergent Mississippian period.  Large public projects were begun during this time. The first evidence of social stratification was seen, in the form of elaborate burials and evidence of sacrifices.  Exotic items have also been found that are thought to date to this period, which is taken as further evidence of social stratification (with the elite controlling access to these items).

The Stirling Phase (A.D. 1050/1100 to 1150/1200)
Regional population peaked during this phase, with increases estimated to be from as little as 4% to as high as 53% from Lohmann phase populations.   Households were thought to be more abundant, but with fewer number of people in each household.  This was a time of major expansion, with increased construction and construction of structures meant to have different functions.  The abandonment of some outlying areas was seen, with more of a concentration of population in the urban center.  The first evidence of craft specialization is seen in the Stirling Phase.

The Moorehead Phase (A.D. 1150/1200 to 1250/1275)
Regional population declined an estimated 38-40% from the Stirling Phase.   The final layer had been put in Monks Mound during this phase.  There may have been a phase between Stirling and Moorehead that is yet to be identified.

The Sand Prairie Phase  (A.D. 1250/1275 to 1400/1350)
Not much is known about this period, during which population continued to decline (as much as 43 to 37% of Moorehead population levels according to Milner) and the regional structure was disintegrating.  The scant evidence points to minimal activity at Cahokia during the Sand Prairie Phase.