A cashel is a type of ringfort built from dry-stone walling rather than earthen banks, and they are among the most enduring remnants of early medieval rural life in Ireland, typically dating from roughly the sixth to the tenth centuries. Most were farmsteads, the enclosed homesteads of farming families who built in stone where stone was plentiful, which in the west of Ireland it usually was.

Ringforts of all kinds number in the tens of thousands across Ireland, yet individual examples like this one in Glenkeen can remain almost entirely outside the reach of casual enquiry. The specific history of this cashel, including who built it, when it was constructed, and what condition it survives in today, remains difficult to establish without access to physical survey records. What can be said is that Glenkeen sits in a part of Mayo where such monuments are not uncommon, tucked into a landscape shaped equally by geology, agriculture, and a long human presence stretching back well before the Norman period.