The example at Thomastown in County Clare is a rath, the term used for a ringfort constructed primarily from earthworks rather than stone, typically a circular bank and ditch enclosing a domestic space. These were the farmsteads of early medieval Ireland, occupied roughly between the fifth and twelfth centuries, places where a family and their livestock sheltered within a raised perimeter that was as much a statement of social standing as a practical defence.

Clare is especially rich in such monuments, its landscape shaped by centuries of early medieval settlement patterns that left rings and enclosures pressed into the ground across townlands throughout the county. Thomastown, like many Irish placenames, likely reflects a later medieval layer of naming, but the earthwork beneath the name is considerably older, a remnant of a way of life that predates the Norman influence that brought surnames like Thomas into common use in Ireland. The rath would originally have enclosed a house, perhaps ancillary buildings, and a yard, the whole surrounded by that characteristic earthen bank which, over the centuries, has softened into the landscape without entirely disappearing from it.