In Western Europe, the transition from the middle Iron Age to the early Roman period implied changes in livestock practices, with the emergence of a specialized and selective animal husbandry. These changes have been related in Italy and south of France with changes in livestock management involving their mobility between ecologically complementary areas. The study of this question in the Iberian Peninsula has only been partially investigated through palaeoenvironmental analyses, and the information about the origin and significance of this phenomenon is very scarce. To shed new light on this topic we used an archaeozoological approach, with the application of geometric morphometrics. They were used to study size and shape variability in sheep astragali from 9 sites dating from the middle Iron Age to the early Roman period (5th c. BC–3rd c. AD) and located on the Pyrenees and on the north-eastern Iberian coast as a case study. The results we obtained, combined with Number of Identified Specimens (NISP) and kill-off patterns, showed local specificities in terms of breeding methods and sheep morphologies between the two areas during the middle Iron Age. On the contrary, sheep with similar size and the implementation and development of similar sheep husbandry practices in the Pyrenees and the north-eastern Iberian coast were documented during the early Roman period. These results suggest the existence of livestock links between these two areas during the Roman period, that could be involved a possible movement of sheep between the lowlands and the Pyrenees for the first time.