"The Dorsey is an extensive earthwork which runs through the South Armagh area and is part of a series of Iron Age earthworks, which run roughly across south Ulster. It extends for 4km and comprises banks, ditches and a wooden palisade (fence)...
Dorsey derives from the Irish Na Doirse meaning 'the gateways' which might suggest that rather than barring access to Ulaidh, it controlled access into the kingdom."