It is not dramatic from a distance, but what it marks is the footprint of a rath, a type of ringfort that served as the enclosed farmstead of an early medieval Irish family, probably between the sixth and twelfth centuries. The earthen bank still stands to about one and a half metres in height along much of its circuit, enough to give a clear sense of the original enclosure even if the interior is now just open pasture.

The northern portion of the site has not survived as well. At some point, that section was levelled and a stone field boundary was built along its edge, the kind of quiet agricultural reshaping that has altered or erased thousands of similar monuments across Ireland. Ringforts of this type were once the dominant settlement form across the Irish countryside, with tens of thousands recorded nationally, yet a great many have been lost precisely to this gradual process of land improvement and boundary-making. The Kilgreana example was documented as part of a 1994 archaeological survey of the Ballinrobe district, compiled by D. Lavelle and published in association with the Lough Mask and Lough Carra Tourist Development Association, which captured a number of such sites in the area around those two lakes before further changes could obscure them.