Within an area of six sq.km, between the upper Einon and upper Cletwr valleys, are located some 20 recorded round cairns and a stone circle. The cairns include a number with kerb structures and others with the remains of central cists though some are amorphous stone piles. Five of the cairns occupy summit positions on Foel Goch, Esgair Foel-ddu and Moel y Llyn itself, at altitudes of up to 521m. The others occupy positions on lower slopes, mostly below 400m, with a discrete cluster on Llain Wen (in the Cletwr valley) which may also have had a function in field clearance. The stone circle is set on a saddle between Moel-y-garn and Moel-y-llyn at 350m altitude.
Most of the area comprises rocky slopes separated by boggy hollows, basin peat rather than blanket peat, with peaty topsoil elsewhere. No other structures of similar date, such as habitations or settlements have yet been noted. Features related to early agriculture have been located near Cae'r Arglwyddes but probably relate to medieval land use or later activity linked to the formation of the large estates. It is possible that in prehistory the entire area was set aside for ritual and sepulchral purposes. The cemetery is reminiscent of that on Mynydd-y-glog near Hirwaun in south Wales (NPRN 414686).
Most of the sites lie on open or enclosed moorland. Others, including the stone circle, lie on adjacent farmed land.

David Leighton, RCAHMW, 14 May 2013