English historian and anthropologist John K. Campbell arrives at the conclusion that the Sarakatsani must have always lived in—more or less—the same conditions and areas as they were found in his days of research in the mid-1950s. He also highlights the differences between them and the Vlachs, regarding the Sarakatsani as a distinctive social group within the Greek nation. As a result of his field studies of the Sarakatsani of Epirus, Nicholas Hammond, a British historian, considers them descendants of Greek pastoralists living in the region of Gramos and Pindus since the early Byzantine period, who were dispossessed of their pastures by the Vlachs at the latest by the 12th century.