It is a cillín, the Irish term for an unconsecrated burial site used for unbaptised infants, and for centuries these quiet plots existed at the edges of communities, physically and spiritually separate from consecrated ground. Catholic doctrine once held that unbaptised children could not be buried in consecrated earth, and so families interred them instead in liminal places: old ringforts, remote hillsides, the boundaries between fields, or sites already understood to carry some ancient significance. The cillín at Cloonnagleragh is one of hundreds scattered across the west of Ireland, each one a small, largely unmarked record of grief managed outside the official rites of the Church.

The practice was widespread from the medieval period onward, and persisted in rural Ireland well into the twentieth century. These sites rarely carry elaborate monuments. A scatter of small stones, occasionally a low mound, sometimes nothing visible at all above the surface of the grass. That absence is itself part of what makes cilliní so affecting: they were places of quiet, private mourning rather than communal commemoration, and many were known only to the families who used them. The broader landscape of Mayo contains numerous such sites, reflecting both the density of rural settlement in the pre-Famine period and the endurance of older customs around death and burial that sat uneasily alongside official Church practice.