A cashel is a type of ringfort built from stone rather than earth, its defining feature a circular enclosing wall that once protected a farmstead or small settlement. Where earthen ringforts, known as raths, were raised from banked soil and ditches, a cashel relies on dry-stone construction, which in the rocky west of Ireland was simply the most available material to hand. Thousands of ringforts survive across the country, dating broadly from the early medieval period, roughly the fifth to the twelfth centuries, yet each one occupies a particular piece of ground chosen by a particular family or community for reasons that are not always easy to read from the surface.

The name Lismoran itself is suggestive. The element "lis" is an Irish word for a fort or enclosure, and its presence in a place name often signals that a ringfort was once a landmark significant enough to name the surrounding land after. Whether the cashel at Lismoran is the feature that gave the townland its name is the kind of question that draws archaeologists and local historians into productive disagreement. Mayo's landscape preserves a considerable number of these stone enclosures, many of them on elevated or slightly raised ground where they commanded a view over farmland and approached territory. The specific history of this particular site, including when it was built, who occupied it, and what its relationship was to the wider settlement pattern of the area, remains to be fully documented.