The one at Brodullagh in County Mayo is a rath, the term used for a ringfort constructed primarily from earthworks rather than stone, typically comprising one or more circular banks and ditches enclosing a central living area. During the early medieval period, roughly between the fifth and twelfth centuries, these enclosures served as farmsteads for farming families of varying social rank, the scale and complexity of the earthworks often reflecting the status of the household within.

Brodullagh itself is a small townland in Mayo, a county whose landscape carries an unusually dense accumulation of prehistoric and early medieval remains, shaped partly by the relative isolation of the terrain and partly by the thin soils that discouraged deep agricultural disturbance over the centuries. Ringforts in this part of Connacht frequently survive as subtle rises and depressions in rough pasture, their banks worn low but still legible from the right angle or in low winter light when shadows sharpen the contours of the ground.