These sites, known in Irish tradition as cillíní (the singular is cillín), were used for the burial of unbaptised infants, and sometimes stillborn children, suicides, or strangers, those who for one theological reason or another could not be received into consecrated ground. They tend to occupy liminal spaces: the edges of bogs, old earthworks, early medieval enclosures, or townland boundaries, and Kilcornan fits into this quietly melancholy pattern.

The practice of burying unbaptised children apart from the main parish graveyard was a direct consequence of Catholic doctrine on original sin and the concept of limbo, the theological category that held unbaptised souls in a state neither of punishment nor of heavenly reward. For centuries, grieving families had no recourse but to bury these children in secret, usually at night, in unconsecrated land. The cillín was not a place of neglect so much as a place of necessity, and many families maintained a quiet, private attachment to these sites long after official Church attitudes began to soften. The Catholic Church formally revised its position on limbo in 2007, acknowledging it as a hypothesis rather than doctrine, but the cillíní remain in the landscape, most of them unmarked and unrecorded in any formal sense.