Studies on the correlations between spatial distribution of linguistic varieties and genetic structure of populations began by dealing with geographic spaces and extensive linguistic families. In the last two decades, researchers with this type of interdisciplinary approach have also begun to study more reduced linguistic and population domains. This paper examines geolinguistic and onomastic information in a linguistic and administrative space of a limited extension of the Principality of Asturias. The information on the surnames of this region, taken from the inhabitants’ register, is used to identify surname regions and check correlations with dialect areas described in this space. The results obtained in this research show many similarities in the distribution of surname regions with dialect areas recognized by traditional dialectology studies. The conclusions of the study present the results obtained together with some of the explanatory proposals on the historical constitution of the linguistic diversity of this area.