Miss Potter's beloved Herdwick sheep were probably introduced by Norse settlers between the 10th and 11th centuries during the Viking invasions. The husbandry of Herdwick sheep has been a large factor in shaping the culture and terrain of the Lake District in NW England. Beatrix Potter was involved with breeding Herdwicks, acting as president of the breed association for a time. She bequeathed fifteen farms to the National Trust, and per her instructions all continue to graze Herdwick flocks.