The range lies between two other ranges, the Galloway Hills to the west and the Lowther Hills to the east. The overall shape of this hill area is oval with the longer curved sides to top and bottom. From the north western point of the oval at Dalmellington to the south eastern one at Thornhill is around 39 kilometres (as the crow flies), though Dalmellington lies some 10 kilometres further north than Thornhill. So the axis of the oval runs from north west to south east. Taking a section across the west end of the oval, from New Cumnock in the north to Carsphairn in the south it is over 19 kilometres and on the east a similar cross section from Sanquhar to Moniaive is almost the same (19 kilometres). The north west quarter of the oval lies in Ayrshire in Strathclyde Region and the other three quarters are in Dumfries and Galloway.