 According to his reconstruction, around A.D. 1050 pre-Cahokia settlements had been suddenly transformed into the large, planned community of Cahokia proper, marked by a sudden preponderance of houses and the rapid adoption of wall-trench housing that replaced the previously common post-wall housing.Also during this time, a series of farmsteads was developed upland from Cahokia proper, and are known as the Richland complex.Their walls were set into trenches, but some post-wall and hybrid-wall forms are present.