A rath, in Irish archaeological terms, is an early medieval enclosure, typically defined by one or more earthen banks and ditches, that once served as a farmstead or defended homestead. At Carhoon, even that outline is gone. The present farm buildings and yard of Carhoon House are thought to occupy the area where the enclosure once stood, and nothing of it is now visible above ground level.

The site has a paper trail of sorts, if not a physical one. A map of 1775, drawn by a cartographer named B. Scalé, marks a large penannular enclosure here under the label 'Danish Fort', a term commonly applied to ringforts in the eighteenth century, when they were popularly attributed to Viking settlers rather than to the earlier Gaelic population who almost certainly built them. Scalé's map also notes a slate house and garden occupying the south-eastern arc of the enclosure, which may explain why that portion of the earthwork appears incomplete on his survey. By the early twentieth century, the scholar Ó Riordáin recorded a local account that 'In Bateman's farm there is said to have been a lios, now cleared away', the word lios being another Irish term for such an enclosure. The Bateman family, who owned the land, had apparently been using part of the rath as a haggard, an enclosed yard for storing hay and grain, its curved boundary wall following the line of the old bank. That boundary was levelled in the 1930s and the haggard extended, completing a process of erasure that had been underway for at least two centuries.