In this paper, we present a documentary reference to the “Guzmango language” in early colonial Cajamarca (Peru), which we then contextualize and discuss. In light of this information, we revisit the debate on the relationship between toponymic areas, languages, peoples, and political units of the past in this region, examining the notion of “contained linguistic area”. We put forward a preliminary equivalence between the “Guzmango language” and the “Den language”, as defined by Alfredo Torero, while discussing its limitations.