Megalithic tombs, a broad category that includes court tombs, portal tombs, and passage tombs, were built roughly between 4000 and 2000 BC, and Mayo holds a notable concentration of them. They were communal monuments, places where the dead were interred and the living gathered, their massive stone chambers and capstones requiring organised labour and, presumably, considerable social purpose.

Killedan itself is a quiet townland, and the tomb there sits within a county that has yielded some of Ireland's most significant prehistoric remains. Mayo's boglands have in many cases both preserved and obscured these structures over the millennia, with peat growth slowly absorbing field systems, pathways, and monuments that were already ancient when Christianity arrived in Ireland. A megalithic tomb in this landscape is not unusual in itself, but the simple fact of its presence connects a particular patch of south Mayo to a tradition of monument-building that stretched across Atlantic Europe.