The rath at Pollnagawna in County Mayo is one such site, a circular earthwork enclosure of the kind that once served as a farmstead or residence for a family of some local standing during the early medieval period, roughly between the fifth and twelfth centuries. A rath, to distinguish it from its stone-built equivalent the cashel, is typically defined by one or more earthen banks and ditches thrown up around a central living area, the whole arrangement functioning as a combination of status symbol and practical boundary against livestock straying and neighbours encroaching.

Pollnagawna itself is a quiet townland in Mayo, a county whose boggy, marginal terrain preserves earthworks unusually well precisely because later intensive agriculture never fully broke the ground. The name Pollnagawna, from the Irish, carries the kind of topographical flavour common to this part of Connacht, where place names tend to encode something practical about the land, a hollow, a water feature, a stand of trees. Ringforts in this region were not military installations in any meaningful sense, despite what the word fort implies to a modern ear. They were the domestic units of a pastoral society, the enclosed yards of farmers who measured wealth in cattle and social rank in the size of their earthen bank. That a site at Pollnagawna preserves one of these enclosures places it within a pattern of early medieval settlement that once covered the whole of the island, most of it now ploughed flat or built over.