These sites, known in Irish as cillíní (singular cillín), were informal, unconsecrated burial grounds used for infants who died before baptism, as well as for others who, under Catholic tradition, could not be interred in consecrated ground. For centuries, unbaptised children were considered ineligible for Christian burial, and so families carried them, often at night and with little ceremony, to marginal ground: old ringforts, cliff edges, boundaries between townlands, or ancient earthworks. The grief was real; the silence around it was enforced by theology.

The name Dumha Thuama is itself quietly telling. "Dumha" in Irish refers to a mound or burial mound, and the pairing with "tuama," meaning tomb or grave, suggests this ground had funerary associations long before any cillín was established here. It is not unusual for such children's burial grounds to occupy prehistoric earthworks or mounds; the unconsecrated and the ancient were, in the minds of rural communities, similarly set apart from the ordinary Christian order of things. The practice of using cillíní continued in parts of Ireland well into the twentieth century, and the sites are now recognised as places of genuine archaeological and social significance, carrying the largely undocumented grief of communities across many generations.