Known in Irish as a ráth, this type of enclosure, typically a roughly circular area defined by one or more earthen banks and ditches, was the standard form of rural settlement in early medieval Ireland, home to farming families of modest to middling standing. Tens of thousands of them survive across the country in varying states of completeness, and yet each one represents a specific choice, a family or community that looked at a particular patch of ground and decided to build their lives there.

The Kerry landscape is thick with such sites, shaped by centuries of pastoral farming and the kind of dispersed rural settlement that made the ráth so practical a form. The earthworks would have enclosed a homestead, perhaps a house or two, animal pens, and storage structures, all ringed by a bank designed less for serious military defence than for keeping livestock in and wolves or opportunistic neighbours out. In many parts of Kerry the underlying geology, the press of bog, the thin upland soils, has preserved these earthworks better than in areas where intensive ploughing has done its flattening work over the centuries. Crag, like many Kerry townlands, carries its archaeology close to the surface.