A coastal promontory fort works on a straightforward principle: the sea does most of the work, dropping away on three sides, while a constructed barrier, typically an earthen bank or stone wall, seals off the landward approach. The result is an enclosure that required far less effort to defend than an inland ringfort, and the Atlantic itself served as the western wall.

Promontory forts of this type are found in some numbers along the west coast of Ireland, and most are thought to date broadly to the Iron Age or early medieval period, though many remain undated through excavation. Their precise function is still debated: some were likely defended settlements, others perhaps seasonal enclosures for livestock, and a few may have served as places of refuge during periods of coastal raiding. The Corbally example sits within this wider tradition, occupying ground where the interaction between human construction and coastal erosion has likely been reshaping the monument for centuries. What survives today may be a considerably reduced version of whatever was originally built.