It occupies the interior of a rath, a type of circular earthwork enclosure built during the early medieval period, typically as a farmstead or settlement defended by one or more banks and ditches. That such a space was repurposed for the burial of children, rather than left to agricultural use or simply abandoned, says something about how communities negotiated between the practical, the sacred, and the liminal.

The use of this rath as a children's burial ground is recorded on Ordnance Survey six-inch maps from both 1838 and 1920, suggesting the practice spanned at least several generations, if not longer. These sites, sometimes called cillíní or killeens, were used across Ireland for unbaptised infants and others who, under Catholic Church practice, could not be buried in consecrated ground. Ancient earthworks like raths were frequently chosen for such purposes, perhaps because they already carried an air of separateness from the everyday landscape, or because local tradition associated them with a kind of otherworldly threshold. Within the rath at Tonnagh, a few low stones protrude from the grass, and these may be grave markers, though they are modest enough that they could easily be overlooked by someone who did not know what they were looking at.