In this paper we analyze the problems set up in border lands, especially when a confluence of linguistic norms has taken place; an example is what happened in the Kingdom of Murcia along the Low Middle Ages, where settlers of different origins and also of different religion or race, Christians (Castilians and Catalans), Mussulmans or Jews lived together during some periods and followed one another in other time, leaving their traces on the onomastics and the toponymy. Some times the settlers' mark remained in the way of naming, but other times they reduced themselves to translate the names given by preceding settlers. With regard to onomastics, the traditions of each people remained evident and so have transmitted along the centuries; in the XIIIth. century it is very important the Catalan influence, a reflex of the repopulations; in the XIVth. century instead, because of the predominance of the Castilian model, a graphic adaptation of the family names received from preceding stages took place. Analyzing the documentation of that age permits us verify that the life together of peoples and languages enriched the toponomastic stock.