The Shetland Sheepdog is probably a descendant from the Rough Collies brought to Shetland (a Scottish island) and mixed with the Icelandic Yakkin, a small dog that is no longer recognized.
By 1700, the breed was totally developed and was used to herd and guard sheep. The Sheltie was first recognized in 1909 in England and brought in the United States in 1911.