The example at Carbad Beg, in County Mayo, is one such site: a rath, which is the Irish term for a roughly circular enclosure defined by an earthen bank and ditch, typically dating from the early medieval period, roughly the fifth to the twelfth century. These structures served as farmsteads and defended homesteads for farming families of middling status, and the sheer number of them that survive, however eroded, speaks to how densely settled the Irish countryside once was.

Raths were built not by kings or monasteries but by ordinary rural households, and their earthworks were meant to keep livestock in and wolves or rival neighbours out. Mayo, with its complex mix of bogland, drumlin country, and Atlantic coastline, preserves a considerable number of these features, many of them now little more than a raised ring in a field, legible from the air or on a calm winter morning when low light throws the earthworks into relief. The townland name Carbad Beg, meaning roughly "small chariot" or possibly derived from an older placename element, hints at the layered Gaelic geography that underlies this part of the west, where ringforts sit within a landscape still largely named in Irish.