The gentle Calculpech built the Standing Stones, though they have long since fled to Kilmorph's vault. The wide eyed Calculpech and troublesome groundhogs once dwelt in the once beautiful valley Gower found ruined by the Godswar.
I'm thinking that Calculpech isn't a who, but rather a what -- some sort of earth elemental, Kilmorph's equivalent to Mulcarn's Frostlings. If I had to guess, I'd say the same is a combination of calculus (in the original meaning of little pebble) and the pech, a type of gnome-like creatures of Scottish mythology that are thought to have built the country's ancient stone megaliths.
I suppose it could also have been a human society loyal to Kilmorph that were wiped out before the creation of the Dwarves, but I prefer to see them as small earth elementals.