The site was recorded on the 1841 Ordnance Survey six-inch map under the name Tonakilla Fort, identified there as a cashel, the term for a stone-walled ringfort of the early medieval period, roughly circular and originally used to enclose a farmstead or settlement. By the time those surveyors arrived, the cashel, which measured approximately 41 metres in diameter, was already levelled. What they found instead was a burial ground inside its perimeter, a pattern that appears repeatedly in the Irish countryside, where the boundary of an old enclosure was quietly repurposed as a cillín, a children's burial ground. These were places set aside for infants who had died before baptism and were therefore excluded from consecrated ground. The practice speaks to a pragmatic, and sometimes heartbreaking, relationship between living communities and the ancient structures around them.

The 1841 map records more than just the cashel and its reuse. Immediately to the south lay additional graves, and nearby a cluster of stones was annotated as Gallauns, a term for standing stones or upright megalithic slabs, possibly the remnants of a much older prehistoric structure. By the time the 25-inch Ordnance Survey map was produced later in the nineteenth century, the cashel appeared only as a roughly circular area defined by a scarp, a low edge in the ground, and the gallauns had been reduced to a notation of their former site. The layering here is considerable: a possible prehistoric megalithic feature, overlaid by an early medieval stone enclosure, which was in turn adopted as a burial place for the unbaptised, all within a few hundred metres of the medieval church and graveyard at Annagh, 370 metres to the east. Nothing visible now marks the spot at ground level.