Shell middens in particular are among the oldest surviving traces of human settlement along Ireland's Atlantic coast, built up over generations as communities discarded oyster shells, fish bones, animal remains, and broken pottery. What looks like refuse is, to an archaeologist, a detailed record of diet, season, and daily life stretching back in some cases thousands of years.

Killadangan sits on the south shore of Clew Bay, a coastline long associated with human activity from the prehistoric period through to the early medieval. The bay's sheltered inlets and abundant marine resources made it an attractive place to settle, and middens along this stretch of Mayo represent some of the earliest evidence of that occupation. Without more specific detail available about this particular deposit, it is difficult to say precisely when it was accumulated or by whom, but its presence in the archaeological record marks the spot as somewhere people returned to, ate, worked, and left their mark in the most ordinary way possible.