The name translates roughly as "cooking place of the Fianna" (a reference to the legendary warrior band), though the term is more romantic than precise. These sites typically date from the Bronze Age, somewhere between 1500 and 500 BC, and they are found in their thousands throughout Ireland, almost always near a water source. The working theory, supported by experimental archaeology, is that they were used for heating water by dropping fire-cracked stones into a trough, then using that water to cook, to process hides, or possibly to bathe. The distinctive mound shape comes from the gradual accumulation of those spent, shattered stones, discarded after each use.

The Cashel site is one of countless such monuments scattered across Mayo, a county whose boggy, water-retentive landscape offered ideal conditions for the kind of activity these sites represent. Fulachtaí fia tend to survive well precisely because they were built up over time in low-lying, often marshy ground that later became preserved under peat. That same peat has made them difficult to farm and easy to overlook, which is part of why so many have endured into the present day, quietly sitting in fields and on bog margins without drawing much attention.