That gap is itself a kind of fact. Ireland's landscape holds hundreds of such enclosures, circular or subcircular boundaries defined by earthen banks, stone walls, or ditches, and they range in date and purpose from prehistoric settlement boundaries to early medieval ringforts used as farmsteads. Which category the Listernan example belongs to, how large it is, how much of it survives, and what relationship it has to the surrounding townland are details that remain, for now, out of reach.

The townland name Listernan may offer a faint clue. Many Mayo placenames carry traces of earlier Gaelic or even pre-Gaelic descriptors, sometimes encoding a feature of the land itself, a fort, a ridge, a watercourse. Without more specific documentation, though, reading too much into the name risks speculation rather than history. What can be said is that enclosures of this kind were typically sited with practical logic, on well-drained ground, near water, with visibility across the surrounding terrain, and that west Connacht was densely settled across many periods, leaving behind a palimpsest of earthworks that still surfaces in fields and along field margins throughout the county.