The following study compares the distribution of surnames in the populations of Western Slovenian municipalities, which were part of the Italian state until the end of the Second World War. The analyses have been carried out firstly by assessing the similarity of different populations to one another so as to verify possible aggregations; secondly, by figuring these relationships of similarity in a representation through unrooted tree (NJ); finally, by applying spatial autocorrelation to the distribution of surnames in the territory so as to highlight possible processes in the diffusion of people in the area under examination. On the whole, it seems likely that the population living in the area is geographically quite stable, although some differences may be noted depending both on the geography of the territory, particularly in the northern part, and on peculiar historical and socioeconomic conditions, which at the same time have characterized and modified the demographic structure of some of these municipalities
