 It may earlier have been a negotiated frontier between Wessex and the British kingdom of Dumnonia which was important in the later development of the West Saxon shires, and later boundaries between Wiltshire and Somerset and north Dorset run through the forest.The boundaries through the forest and Bokerley Dyke which separated Somerset and Dorset from eastern counties may date to the fifth or sixth centuries.Selwood's importance as a boundary was also recognised in 705 when the bishopric of Sherborne was established for those "west of Selwood".