These enclosures, known in Irish as raths, were the ordinary farmsteads of early medieval Ireland, typically dating from roughly the fifth to the twelfth century. A raised earthen bank, sometimes accompanied by a ditch, defined the boundary of a family's living space and offered a modest degree of protection for people and livestock alike. They are among the most common archaeological monument types in the country, yet each one represents a specific household, a specific choice of ground, and a specific moment when someone decided this particular patch of Clare was worth settling.

Raths were not fortresses in any military sense. The bank and fosse, the ditch dug to provide material for the bank, would have deterred a wandering animal more reliably than a determined raider. Inside, the enclosure would have held a timber or wattle house, perhaps a souterrain, an underground stone-lined passage used for storage or refuge, and the ordinary clutter of early medieval rural life. The name Ballyonan itself, like most Irish townland names, almost certainly preserves older Gaelic elements that would have been in everyday use when the rath was still occupied, though the precise etymology here is not recorded in available sources.

Clare is particularly rich in these monuments, its karst limestone landscape and relatively low modern development having preserved earthworks that elsewhere were ploughed out or built over during the eighteenth and nineteenth centuries. That survival is part of what makes a site like this worth pausing over, even when the documentary record is thin. The mound or bank, however grass-covered and unassuming, is a direct physical remnant of an agricultural community going about its life in the early centuries of the first millennium, long before the Norman arrivals restructured landholding across the island.