Ringforts, known in Irish as raths, were the most common form of rural settlement in early medieval Ireland, typically consisting of a circular area enclosed by one or more earthen banks and ditches. They served as farmsteads, the home ground of a single family and their livestock, and tens of thousands of them once dotted the countryside. That so many survive at all, even in partial form, is largely down to a long-standing rural unease about disturbing them, rooted in their association with the sídhe, the fairy mounds of Irish tradition.

The Killeen example is one of countless such sites recorded across Mayo, a county whose relatively low levels of intensive modern agriculture have allowed many early medieval earthworks to endure where elsewhere they have been ploughed flat. The townland name Killeen itself derives from the Irish cillín, a word that can denote a small church or, more specifically, an unconsecrated burial ground, suggesting that this particular patch of Mayo has drawn human attention and use across many centuries and for more than one purpose.