the swaledales as a breed are related to scottish blackface and rough fell sheep, both of which are also predominant in upland locations in the united kingdom and noted for their ability to thrive in exposed locations. although the specific origins of the breed are unknown, a non-indigenous and exotic ancestor for the swaledale was considered by two noted names of the eighteenth century, john naismyth and charles findlater. published in 1796, naismyth's opinion in "young's annals of agriculture" was that the origin of the black-faced highland breeds was "impossible to trace". robert trow-smith in his book "a history of british livestock husbandry, 1700–1900" wrote: "... it has already been suggested that this family stood outside the main stream of ancient british sheep..." and that the root of the swaledale and scottish blackface breeds could be the argali. this tenuous link between domestic sheep and the wild argali has since been proved to be insupportable due to a significant difference in genetic make-up and number of chromosomes.