Known in Irish as cillíní, these were sites set apart from consecrated ground, used for centuries to inter unbaptised infants and others who, under Catholic Church doctrine, could not be buried in a parish churchyard. The one at Cuillonaghtan in County Mayo is one such place, quietly present in the landscape, carrying the weight of a practice that continued in some areas well into the twentieth century.

The tradition behind these grounds reflects a theology, now largely abandoned, that held unbaptised children to be excluded from Heaven and therefore ineligible for burial in sanctified soil. Families, unwilling to leave their children entirely unmarked, turned instead to liminal spaces: old ringfort enclosures, the margins of fields, cliff edges, and early medieval ecclesiastical sites whose pre-Norman origins placed them outside the formal parish system. These locations were neither fully sacred nor fully secular, and in that ambiguity they served a quiet, practical grief. Cuillonaghtan sits within this tradition, its name and location in Mayo placing it in a county where such sites are relatively well documented, if seldom visited or interpreted for the public.

Because detailed records for this particular site have not yet been made widely available, the specifics of its history, its extent, and any associated features remain difficult to describe with precision. What can be said is that these grounds, wherever they occur, tend to be modest in appearance, sometimes marked by small stones, sometimes not marked at all, and that their significance lies less in any visible monument than in what their existence tells us about how ordinary families navigated loss, doctrine, and the land itself.