No one is really sure when the working sheepdog became a fundamental part of keeping sheep on the huge open hills of the border country between Scotland and England. The dogs were certainly basic to the economy of this area by the 18th century and by the end of the 19th century the sport of dog trialing had become widespread in not only this area but across the British Isles.
As farmers and shepherds began to travel outside of their own areas with their dogs the working dogs of different areas were interbred. The type of working dog that we today identify as the Border Collie was well fixed by the 20th century through a combination of selecting for the best working dogs on the hills and farms and in dog trials across the UK. In all of this selecting and breeding of sheepdogs, long before the dogs were identified as Border Collies, the criteria was to find the dog best able to assist the shepherd in managing large numbers of semi-wild sheep on great expanses of unfenced, unimproved ground.