Excavations conducted in 2015 and 2016 discovered a unique set of friezes at the Initial period (2100–1000 cal BC) site of Taukachi-Konkán in the coastal Peruvian valley of Casma. At this time, the Casma Valley was dominated by the Sechín Alto polity, a cultural development of unprecedented complexity characterized by large planned cities, monumental constructions, and strong interconnections among component settlements. Friezes are known from all major Sechín Alto polity sites where they typically adorn structure facades; however, the Taukachi-Konkán friezes are unusual because they cover all four interior walls of a sunken court with restricted access. Based on analysis of the context and content of these friezes, we suggest that the collective imagery depicts aspects of Sechín Alto polity cosmology, including possible iconography relating to their creation myth. Furthermore, motifs from the Taukachi-Konkán sunken court can be found at contemporary sites both within and outside the Casma Valley. This suggests that the worldview we reconstructed may have been widespread during the Initial period.