The basic principle is one of elegant economy: where the sea already defends two or three sides of a headland, the builders needed only to cut a ditch or raise a bank across the narrow neck of land to create an enclosure of considerable security. The result is a form of defended settlement found at intervals all along Ireland's western seaboard, most of them raised during the Iron Age, though some were reused or modified well into the early medieval period.

Sáile sits on the north Mayo coast, a stretch of coastline that was never remote from maritime activity, whatever it might look like on a map today. The communities that built and used these coastal forts were oriented toward the sea rather than away from it, and a promontory position offered both protection and a vantage point over the water. The specific history of this particular site, its builders, its occupation, and any finds associated with it, remains largely undocumented in the public record at present.