A cashel is a ringfort built from dry-stone walling rather than earthen banks, and the form is characteristic of early medieval Ireland, roughly the fifth to twelfth centuries, when such enclosures served as the fortified farmsteads of farmers, petty lords, and local dynasties. Tens of thousands of ringforts once dotted the Irish countryside, and while many earthen examples have been levelled by ploughing over the centuries, stone-built cashels have often fared better, their walls too substantial to simply disappear.

The townland name Carrowmore derives from the Irish An Cheathrú Mhór, meaning the big quarter, a reference to an old Gaelic land division. Mayo's western landscape is well suited to dry-stone construction; timber was scarce in many parts of the county, but fieldstone was abundant, gathered from the cleared ground itself. The people who built and occupied these enclosures left few written records, and much of what is understood about their daily lives comes from archaeology rather than text, from evidence of hearths, souterrains (underground passages sometimes used for storage or refuge), and the occasional personal object turned up by careful excavation. Whether this particular cashel has been excavated, and what it may have yielded, remains undocumented in publicly available sources at present.