Kilnagalliagh derives from the Irish Coill na Caillí, meaning the wood of the hag or old woman, a figure who appears with striking regularity in Irish place names associated with prehistoric monuments, high ground, and the kind of landscape that invites legend. That a cairn, a mound of heaped stones typically raised over a prehistoric burial, sits in a townland carrying that name in County Clare is the sort of quiet coincidence that tends not to be a coincidence at all.

Cairns of this type are among the oldest built structures in Ireland, with many dating to the Neolithic or early Bronze Age, roughly between 4000 and 1500 BC. They served most commonly as funerary monuments, sometimes covering a stone-built chamber, sometimes simply marking a place of significance in the landscape. County Clare has a notably varied prehistoric archaeology, from the limestone expanses of the Burren with their well-documented portal tombs and wedge tombs to less-visited sites scattered through the inland parishes. Kilnagalliagh sits among the latter, the kind of site that registers on maps and in monument records without yet having accumulated much in the way of published detail.