A regional group of middle Neolithic long barrows defined in 1969 by Jack Scott and found widely scattered across southwestern Scotland, especially around the Clyde Valley. Scott argued that the Clyde cairns developed out of small simple megalithic structures which he called ‘protomegaliths’, in many cases being the physical elaboration of these early structures on the same site. The Clyde cairns are charac‐terized by rectangular and trapezoidal mounds, stone‐built chambers comprising linear groups of cells at the higher and wider end of the mound, concave or recessed forecourts, and a façade of large stones set around the back of the forecourt, usually diminishing in height outwards from the entrance to the chambers. Collective inhumation is the usual burial rite, although cremations are sometimes present. Grave goods are rare.