This chapter reviews archaeological evidence for culture change during the first millennium ad in north-central Peru, and its implications for the spread of language(s). Important developments deriving from regional interaction typified the first centuries ad (north-west Ancash), the seventh century ad (Callejón de Huaylas), and the end of the Middle Horizon (across departments). If major language expansions can be pegged to transformations in material style, they should be sought in these periods and areas. Many different Amerindian languages are known from the region (Culle, Mochica, Quingnam, Quechua, Aymara), although most are now extinct. The cultural heterogeneity in north-central Peru during the Early Intermediate Period may indicate considerable time-depth for such linguistic diversity. The subsequent Middle Horizon marks a period of widespread interaction, though varying in nature and impact through time. This elicits issues for future research in the linguistic prehistory of the central Andes.