Unlike many miniature breeds that resemble their larger counterparts, this breed was not developed simply by selectively breeding the Rough Collie for smaller and smaller size. The original sheepdog of Shetland was a Spitz-type dog, probably similar to the modern Icelandic Sheepdog. This dog was crossed with mainland working collies brought to the islands, and then after being brought to England, it was further extensively crossed with the Rough Collie, and other breeds including some or all of the extinct Greenland Yakki, the King Charles Spaniel (not the Cavalier), the Pomeranian, and possibly the Border Collie. The original Spitz-type working sheepdog of Shetland is now extinct, having been replaced for herding there by the Border Collie. Shelties were used for herding until commercial livestock farming required larger breeds.