The example at Ballynew in County Mayo is a rath, the term used for an earthen ringfort, typically consisting of one or more circular banks and ditches that once enclosed a farmstead during the early medieval period, roughly between the fifth and twelfth centuries. These were not military fortifications in any grand sense, but the protected homes of farming families, the banks serving as much to keep livestock in as to keep danger out.

Ireland has somewhere in the region of forty to fifty thousand recorded ringforts, and Mayo is well represented among them. The rath at Ballynew sits within that broader pattern of early medieval rural settlement, where individual family units worked their land within a defined, enclosed space. The word rath itself comes from the Old Irish for a circular earthen enclosure, and distinguishes this type from cashels, which are their stone-built equivalents found more commonly in the west and on higher ground. Without more detailed fieldwork notes available for this particular site, what can be said is that its presence in Ballynew places it within a wider web of early Christian-era habitation across the county, a period when such enclosures defined the basic unit of Irish social and agricultural life.

For those wandering the Mayo countryside with an eye for earthworks, a rath typically appears as a low, rounded bank, sometimes barely a metre high, curving in a near-perfect circle around a slightly raised interior. Centuries of ploughing, drainage work, and land clearance have worn many of them down considerably, making them easy to miss unless the light is low and raking across the ground, which is when the subtle relief of an old bank reveals itself most clearly.