By about 1200 AD, however, it looks as if the Mississippian centers were more involved in regional trading and that there was little trade with Cahokia. There are no more platform mounds built in Wisconsin. Archaeologists aren't sure what happened to Cahokia. The complex society that marked Cahokia changes. There are no more platform mounds, the communities are much smaller than Cahokia, and trade networks are greatly reduced. One theory is that it evolved into the Oneota culture.