The same ground was also used, by repute, for the burial of unbaptised infants, placing it within a tradition found across Ireland of liminal, unconsecrated spaces serving as resting places for children who died before receiving baptism. These sites, known in Irish as cilliní, occupy a strange position in the landscape and in memory, neither fully within the community nor entirely apart from it.

The site at Tullig carries both identities at once. The local name of fort suggests an earthwork of some kind, possibly a ringfort, the type of circular enclosure common throughout early medieval Ireland that would have served as a farmstead or place of shelter. Such structures often accumulated secondary associations over the centuries, their enclosing banks providing a boundary that, while not sanctified by the Church, still marked a space apart from the ordinary fields around it. The use of such places for the burial of unbaptised children reflects the difficult position those infants occupied in Catholic theology and rural Irish practice: denied consecrated ground, they were nonetheless given a form of burial in places already considered old, set apart, and in some sense protected.