It sits in a county already thick with ringforts, promontory enclosures, and field boundaries accumulated across several thousand years of settlement, which makes the absence of detail here quietly curious rather than simply administrative. Something was built or shaped in that ground deliberately enough to warrant classification, and that is more or less all that can be said with certainty.

The townland name itself offers a small clue. Tarmon derives from the Irish tearmann, meaning a sanctuary or church land, a term applied in early medieval Ireland to territories under ecclesiastical protection. Such lands were often associated with early monastic foundations and carried particular legal status, exempting them from certain obligations and offering refuge to those within their bounds. Whether the earthwork relates to that ecclesiastical history, to an earlier prehistoric use of the land, or to something altogether different is not known from available sources. The classification as an earthwork is broad enough to cover anything from a low enclosure bank to the remnant of a field system or a burial mound, and without further detail the structure remains stubbornly opaque.