A field system, in archaeological terms, is exactly what it sounds like: the surviving traces of boundaries, banks, walls, or ditches that once divided agricultural land into plots. What makes such systems remarkable is not their drama but their persistence. The boundaries that guided a farmer's plough or a shepherd's flock centuries ago can still be read in the texture of the ground, long after the people who made them are forgotten.

Field systems in the west of Ireland range enormously in age and character, from the celebrated Neolithic landscape preserved beneath the bog at Céide Fields in Mayo, to the post-medieval lazy beds left by runrig cultivation across Connacht. Ballinillaun sits within a county whose landscape has been layered by successive waves of land use, clearance, abandonment, and resettlement. The detail of what survives at this particular site, when it was laid out, by whom, and under what conditions of tenure or subsistence, remains to be established from the available record.