The
Battle of Deorham occurred in
577 between the
West Saxons and the Celts. Deorham is usually taken to refer to
Dyrham, Wiltshire[?]. The battle is considered by some to be decisive since it drove a land wedge between the Celts of what is now (approximately) Wales and those occupying territory to the south-west, e.g. what are (approximately) now
Somerset,
Devon and
Cornwall. However, passage through this area by Welsh-speaking individuals was not impossible: a genealogy of Welsh aristocrats notes that the descendants of kings who ruled in
Powys founded a dynasty of rulers in the
Glastonbury region in the
eighth century.