This is a rath, the Irish term for a ringfort, a form of enclosed farmstead that was the typical dwelling of farming families during the early medieval period, roughly between the fifth and twelfth centuries. Thousands of them survive across Ireland, many reduced to barely a ripple in the ground. This one retains more substance than most: an earthen bank rising to around 1.2 metres, encircling an interior roughly 33 metres across from north to south, with a shallow external fosse, or ditch, still tracing its outer edge at about 0.4 metres deep.

The site was recorded in a 1994 archaeological survey of the Ballinrobe district compiled by D. Lavelle, a study that also took in the landscapes around Lough Mask and Lough Carra. That broader area is one of the more archaeologically dense parts of Connacht, its limestone terrain and lake margins having supported continuous human settlement from prehistory onward. The rath at Kilgreana fits neatly into that pattern, though its position on a steep slope is worth noting. Ringforts are commonly found on elevated ground with good outward views, and a south-facing aspect would have offered both warmth and visibility across the surrounding land.