A midden is essentially a prehistoric or early historic rubbish heap, most commonly composed of shell, animal bone, charcoal, and discarded tools. That description undersells what these deposits actually are: dense, stratified records of how people ate, what they gathered from the shore, and how long they occupied a place. Along the Atlantic coast of Mayo, where communities lived in close relation to both land and sea for millennia, such accumulations can preserve organic material that survives nowhere else.

The place name Tóin An Tseanbhaile carries its own archaeology in miniature. The word "seanbhaile", meaning old settlement or old townland, suggests that the memory of earlier occupation was already encoded in the local landscape long before any modern survey took note of it. Communities frequently named places in relation to what had come before, and a name like this one implies that the midden site sits at or near the edge, the trailing end, of somewhere people once lived in earnest. Without fuller excavation records available, the precise date range of the deposit remains unclear, but coastal middens in the west of Ireland span a broad sweep of time, from Mesolithic shell middens left by hunter-gatherers to accumulations associated with medieval and early modern fishing communities.