These sites are known in Irish as cillíní, and they served a purpose that reflects one of the more sorrowful corners of Catholic practice: unbaptised children, and sometimes others considered to exist outside the boundaries of formal Christian burial, were interred here rather than in consecrated churchyards. The logic was theological, but the locations chosen were often ancient, liminal places, field edges, old ringfort boundaries, or spots already understood to belong to a time before the parish system. The ground at Corraun is one of hundreds of such sites recorded across the country, each one a quiet register of loss.

The tradition of cillíní burial persisted in rural Ireland from the medieval period well into the twentieth century. Parents who lost newborns, or infants who died before a priest could be reached, would bury their children in these unofficial grounds, sometimes at night and without ceremony, the grief compounded by the Church's position that the soul of an unbaptised child could not enter heaven. The sites were generally unmarked in any formal sense, or marked only with small stones, and they were rarely spoken about openly. The Corraun Peninsula, a strip of land reaching into Clew Bay between Achill Sound and the mainland, would have had communities living closely with this practice across generations, the location of the cillín known locally even when unrecorded officially.