The wall follows a sub-circular path, and that rounded outline is not simply a quirk of the local landscape or a surveyor's whim. It is the kind of shape that archaeologists have learned to read carefully, because it frequently marks the ghost of something far earlier.

Early Christian ecclesiastical enclosures, which were the defining spatial feature of the Irish monastery and church settlement from roughly the fifth century onwards, were typically bounded by a circular or oval earthwork, a bank and ditch that set sacred ground apart from the secular world around it. Over the centuries, many of these enclosures were built over, ploughed away, or quietly absorbed into later land use. Graveyards, however, have a habit of preserving the original outline, since communities tend to maintain burial grounds even when every other trace of an early foundation has disappeared. The curved wall at Grange Beg fits this pattern, and the scholar Leo Swan, writing in 1988, identified it as a possible indicator of just such an Early Christian enclosure beneath or around the later graveyard. The word "possibly" is doing real work here; the shape alone is suggestive rather than conclusive, and no excavation record appears to confirm the underlying structure. But the sub-circular form is considered a reliable enough diagnostic that its presence alone warrants attention.