It is a rath, the Irish term for a ringfort, and ringforts of this kind were once among the most common man-made features of the Irish countryside. Roughly forty to fifty thousand are thought to have existed across the island, the majority built between the sixth and tenth centuries as enclosed farmsteads for early medieval families of some local standing. The enclosing bank and ditch offered a degree of protection for livestock and indicated the status of whoever lived within. That so many survive at all, even in degraded form, is largely because they attracted a reputation for supernatural occupancy, associated in folklore with the sídhe, or fairy mounds, which made farmers reluctant to disturb them with a plough.

The Clooncullin example belongs to this broad and ancient tradition, though the particular details of its construction, condition, and history remain sparse. Clare itself is a county with a dense concentration of early medieval remains, from the limestone karst of the Burren, where ringforts are sometimes visible from a considerable distance on open rock, to the more enclosed drumlin and pasture country further east and south. Clooncullin as a place name contains the Irish element cluain, meaning a meadow or fertile riverside plain, which often indicates land that was prized for early settlement. A rath placed in such a location would have made good agricultural sense, its occupants farming the surrounding ground while the enclosing earthwork defined both their territory and their household.