Killeens, from the Irish cillín, were informal burial grounds used for unbaptised infants, and sometimes for others considered ineligible for consecrated ground, including suicides, strangers, and the unbaptised poor. They occupy a quietly melancholy place in Irish rural tradition, neither fully sacred nor fully forgotten, often tucked at the edges of fields, beside old earthworks, or close to ancient ecclesiastical remains. The one at Drumneen is recorded as a monument, which places it within a broader landscape of such sites scattered across Mayo and the rest of the country.

The practice of burying unbaptised children in killeens persisted in Ireland from at least the early Christian period well into the twentieth century. Catholic doctrine held that unbaptised infants could not enter heaven, and church authorities generally refused them burial in consecrated cemeteries. Families, unwilling to leave their children entirely without a resting place, turned instead to spots already associated with antiquity or sanctity, pre-Christian enclosures, early medieval church sites, or simply secluded ground that felt, by long custom, set apart from the ordinary. Many killeens were never formally marked, and a significant number were only identified and recorded in relatively recent decades, often through local memory as much as physical evidence.