| 189 9 Coalescence at Chicoloapan, Mexico Migration and the Making of a Post-Collapse Community SARAH C. CLAYTON DOI: 10.5876/9781646420735.c009 The Epiclassic period, from about ad 550 to 850, was a time of extraordinary social change in central Mexico. The powerful centralized state of Teotihuacan had broken down, its governing institutions dissolved, and the population of its monumental capital diminished to a fraction of its former size. The release of Teotihuacan’s grip transformed a formerly consolidated subject territory into a fractious sociopolitical landscape coping with instability and violent confict (see Morehart et al. 2012). These circumstances stimulated and may have at times necessitated—through displacement or forced relocation, for example—the signifcant movement of people. The reconfguration of settlement across the Basin of Mexico (Charlton and Nichols 1997; Sanders et al. 1979) that resulted from these migrations is among the most archaeologically conspicuous changes related to the state’s decline. As several previously established communities were abandoned, new settlements appeared in defensible locations, such as hill- tops. Some existing settlements experienced rapid and extensive growth, which required solving new sets of problems related to basic provisioning, security, the use of land and resources, and achieving a peaceable coexistence among