The site is a coastal promontory fort, a type of enclosure in which Iron Age or early medieval communities used the natural drama of a cliff-edged peninsula to do much of the defensive work for them. A rampart or series of ramparts, typically of earth or stone, was thrown across the neck of the headland, turning the seaward projection into a fortress with sheer drops on most sides and a single controlled approach on land. It is a form of fortification found right around the Irish coastline, particularly along the western seaboard where the Atlantic has carved the land into exactly the kinds of pointed, wave-lashed fingers these builders favoured.

Knockaun sits in a part of County Mayo where the landscape has never made life straightforward. The combination of exposed Atlantic coastline, thin soils, and the particular geography of the west gave these promontory forts both their purpose and their enduring presence. They were not built by any single culture on a single date but represent a long tradition of coastal occupation and, presumably, the need to watch the sea, control it, or simply withdraw to it when circumstances demanded. The specific history of this particular fort, its builders, the period of its construction, and whatever evidence of occupation survives on the ground, remains to be fully documented and made publicly available.