Most ancient routes leave some trace in the archaeology beneath them, a shard, a layer of old metalling, an organic material that a radiocarbon sample can pin to a century. The trackway running through the bog and marginal land of the Nephin Beg range in County Mayo has so far yielded nothing of the sort. Excavations uncovered unpaved sections, but the ground gave up no dating evidence whatsoever, leaving the route in a kind of historical suspension, known to exist, impossible to place.

When Ó Ríordáin and Mac Dermott investigated the road in the early 1950s, they found something that complicated any simple verdict. The road traces what appears to be a natural line of travel, running along the valley from Sramore, passing close to a rath (a roughly circular, raised earthwork enclosure associated with early medieval settlement in Ireland) and alongside a fording point on the Goulaun River, before continuing north-east through the mountain pass above Bunaleeva Lough. The geography itself argues for antiquity: this is precisely where a person crossing this terrain on foot or with animals would logically go. The researchers concluded that it is reasonable to believe the road coincides with an old route used from early times, while acknowledging that the physical construction may be of relatively modern date. In other words, people almost certainly walked this line for centuries before anyone thought to surface it formally, and by the time they did, they left nothing behind that would tell us when.

Today the road exists in two distinct states. The south-western portion, near the rath, is maintained by Coillte, the state forestry company, as an access route through commercial woodland. The north-eastern stretch, as it climbs toward the pass, has been given a modern tarmacadamed surface. The ancient and the mundane share the same alignment, as they so often do in Ireland, the practical logic of the landscape quietly outlasting every era that has moved across it.