A rathduff designation suggests a site of some antiquity, most likely an earthen ringfort of the early medieval period, the kind of circular enclosure that farmers and cattle-keepers built across Ireland roughly between the fifth and twelfth centuries as a combination of homestead and livestock enclosure. Tens of thousands of these survive in varying states across the country, but each one carries its own local identity, shaped by the landscape it occupies and the families who once lived within its banks.

Mayo is a county dense with such remains, and the Behy area sits within a landscape that has been farmed and settled since prehistoric times. The name Behy itself derives from the Irish beitheach, generally understood to refer to a place of birch trees, which gives a small suggestion of what the terrain may once have looked like before centuries of agricultural clearance. Ringforts, known variously as raths or lios depending on regional usage, were typically defined by one or more circular earthen banks and ditches, enclosing a space where a family would have kept their home and animals safe from opportunistic raiding. The "duff" or dubh element in Rathduff may refer to the colour of the soil, the shade cast by surrounding vegetation, or simply a distinguishing local nickname that stuck across generations of place-name use.

Beyond the name and its probable category as an early medieval earthwork, the specific details of this particular site remain largely inaccessible at present, with formal documentation still pending in the national record. What is certain is that the name itself has survived, which is often the most durable kind of evidence a place can offer.