Heledd
A Northumbrian raiding party led by Oswiu of Northumbria overran a Welsh king Cynddylan's palace at Llys Pengwern (which is now in England in a surprise attack. Caught completely off guard and without defence, the royal family, including the king, were slaughtered. The Welsh Kingdom of Pengwern was no more. Princess Heledd was the only survivor and fled to western Powys. She went on to write Canu Heledd (songs of Heledd) which is a "collection of early Welsh englyn-poems. They are rare among medieval Welsh poems for being set in the mouth of a female character." They show the heartache felt after losing her family and her kingdom After this the region associated with Pengwern seems to have been shared between Mercia and Powys; part of it remained in Welsh hands until the reign of Offa of Mercia and the construction of his dyke. Part of it consisted of the Anglian sub-kingdom of the Magonsæte. Princess Heledds words are in the link below. http://www.kmatthews.org.uk/his