In 17th century were use for grazing only big dogs which were guardian of flock against big wild beast. These dogs were lash near building of herdsman and were use only in danger. Other works with flock made herdsman alone.
The second part of 17th century was period of fast changes. Big wild beast became rare, flocks were bigger and bigger. Herdsman's care about flocks beyond his depth. In this time began use other dogs (smaller, faster, easy to operate).
Sheep breeding at Brithis islands is the one of biggest part of these agricultural. Because of it there arised many dog breeds use for flocks grazing (collie, sheltie, bobtail, bearded collie, welshcorgi, cumberland sheepdog, border collie etc.). Some of these breeds care a namo collie instead they aren't relation.
Name of collie arised clearly from name of sheep - coalley (for these breed was typical black head). Dogs, which grazes these sheeps were call coalley dogs, later coalley, than colly and now collie. So same name collie was use for dog from different breeds, which work with sheeps.
In history we have two lines of sheepdogs. First was from Tiber terrier (small one, long hairs) and second one from Tibet bandog (big one, short hairs). To the first one we can sort border collie, to the second one bobtail, cumberlan sheepdog and bearded collie. Sheltie and welshcorgi are out of these separation, they make third independent line of sheepdogs.
Collie is known in two forms - smooth and rough. FCI allowed interbreeding between smooth and rough collies because of not going to extinction of them. Collie is original European breed, it isn't in relation wiht other Brithis breeds instead of sheltie.
For better looks of collie were interbreed barzoj, gordonsetter probably in second half of 17th century.
All dogs of collie breed have in direct blood line one constituent studdog - famous English "TREFOILA", which was written into studbook in 1873(magazine PES - přítel člověka, r. 1983).