The example at Ballynew in County Mayo is a rath, the most common type of ringfort, consisting essentially of a roughly circular enclosure defined by one or more earthen banks and ditches. These were the farmsteads of early medieval Ireland, occupied roughly between the fifth and twelfth centuries, and their sheer abundance means that many sit in fields without a signpost or a footnote, known mainly to the farmer whose tractor passes them each spring.

A rath was a working settlement, not a ceremonial site or a fortress in any military sense. The bank and ditch provided security against wolves and cattle raiders rather than armies, and the interior would have held a timber house, outbuildings, and perhaps a small garden plot. The name Ballynew itself is an anglicisation of an Irish place name suggesting a newer or younger townland settlement, a hint that the landscape here has been continuously shaped by the people living in it across many centuries. County Mayo has a particularly dense concentration of such earthworks, partly because its Atlantic boglands have preserved features that more intensively farmed counties have long since ploughed flat.