The example at Treanbeg, in County Mayo, does something quietly different: it is classified as an inland promontory fort, meaning its builders found a natural spur of elevated ground, perhaps a ridge above a river valley or a tongue of land between two slopes, and applied the same defensive logic far from any shoreline. That distinction alone makes it an unusual entry in the catalogue of Irish prehistoric enclosures.

Inland promontory forts are relatively rare in the Irish archaeological record, and their distribution across Connacht suggests communities in the west were adept at reading the landscape for natural defensive advantages wherever those could be found, coastal or otherwise. The form itself belongs broadly to the Iron Age, though some examples were constructed earlier and others continued in use well beyond that period. At Treanbeg, the specific details of construction, the number and extent of any earthen banks, the presence of an entrance, and the internal area enclosed, remain to be fully documented in the public record. What can be said is that the site preserves evidence of a community that chose this particular piece of Mayo ground and shaped it deliberately, cutting it off from the surrounding terrain in a way that still registers, however faintly, in the topography today.