These small, stone-built chambers, sometimes called tigh allais in Irish, functioned as a kind of rudimentary sauna. A fire would be lit inside, the embers raked out once the walls had absorbed enough heat, and a person would crawl in through the low entrance and sweat in the darkness, often before plunging into a nearby stream. They are found across Ulster and Connacht in particular, and most are thought to date from the medieval period through to the eighteenth or early nineteenth century, though they may have older antecedents. Their exact medical purpose is debated, but rheumatism and skin conditions are most commonly cited in folklore accounts.

Beyond its classification and location, the specific history of the Cornagashlaun example remains poorly documented in the public record. What can be said is that Mayo contains a number of these structures, most of them modest and easy to overlook in the landscape, their corbelled or lintelled roofs sometimes half-collapsed and overgrown. They were not monuments in any ceremonial sense; they were functional, almost domestic, and that ordinariness is part of what makes their survival interesting. A structure built for weekly use by farming people, rather than for ritual or commemoration, was rarely maintained once the practice fell out of fashion, and yet many have endured simply because the drystone construction was solid and the land around them was never dramatically altered.