These circular enclosures, known in Irish as raths, were the farmsteads of early medieval Ireland, typically defined by one or more earthen banks and ditches thrown up around a central living area. They were not primarily military structures, despite what the word "fort" implies, but rather the domestic and agricultural headquarters of farming families, their livestock, and whatever small wealth they had accumulated. Ireland contains thousands of them, and yet each one occupies a specific patch of ground that was chosen deliberately, farmed intensively, and eventually abandoned, leaving a circular scar that has outlasted the people who made it by more than a millennium.

The Greygrove example sits within a county that is unusually dense with such monuments. Clare's underlying limestone geology, which gives the Burren its famously spare and legible surface, has helped preserve earthworks that elsewhere have been ploughed flat or swallowed by development. Raths in this part of Ireland date broadly to the early medieval period, roughly the fifth to the twelfth centuries, though many continued in some form of use or memory long after that. Local folklore frequently attached supernatural significance to these enclosures, associating them with the sídhe, or fairy mounds, which gave added incentive not to disturb them and may partly account for their survival in the agricultural record.