Although archaeologists have become increasingly interested in disaster, collapse and regeneration, there has been insufficient attention paid to the social and psychological impact of disasters. Disasters can stimulate far-reaching religious changes. This article is a case study of the fall of the Middle Sicán polity of northern Peru (ad 900–1100) that draws on both archaeology and oral tradition. Middle Sicán cosmology was centred on the Sicán Deity, which did not survive the polity's collapse. The god's demise and the revitalization movement that followed the Middle Sicán can only be understood by considering both how many of the people of the region conceptualized their world and the disasters that occurred.