When the outer rampart of the hillfort was cleared in 1994 as part of the Discovery Programme North Munster Project, surveyors found the footings of an earlier enclosure wall sitting underneath a cashel, a type of stone-built circular enclosure common in early medieval Ireland, and extending slightly to the south and east. The identifiable portion of this earlier wall measured less than 34 metres in diameter, making it somewhat smaller than the cashel that was later built over it. Its construction followed a recognisable technique: large stones forming an outer facing, with rubble packed into the core behind them.

What makes the find quietly significant is what it implies about the sequence of activity on this hillside. According to the analysis by Condit and Grogan, published in 2005, this earlier enclosure may have been organised around a low platform feature identified in the same area, and may actually pre-date the hillfort itself. Mooghaun is already one of the largest later Bronze Age hillforts in Ireland, a site of considerable complexity, so the suggestion that it was built over or around an even older enclosed space adds another layer to a history that was already difficult to read. The wall footings alone do not settle the question of date or function, but they point to this corner of the ridge having held some importance before the great ramparts were ever raised.