Powys and other British kingdoms were defeated by the Northumbrians under Æthelfrith, with king Selyf ap Cynan among the dead. It has been suggested that this battle finally severed the land connection between Wales and the kingdoms of the Hen Ogledd ("Old North"), the Brythonic-speaking regions of what is now southern Scotland and northern England, including Rheged, Strathclyde, Elmet and Gododdin, where Old Welsh was also spoken. From the 8th century on, Wales was by far the largest of the three remnant Brythonic areas in Britain, the other two being the Hen Ogledd and Cornwall.Wales was divided into a number of separate kingdoms, the largest of these being Gwynedd in northwest Wales and Powys in east Wales. Gwynedd was the most powerful of these kingdoms in the 6th century and 7th century, under rulers such as Maelgwn Gwynedd (died 547) and Cadwallon ap Cadfan (died 634/5), who in alliance with Penda of Mercia was able to lead his armies as far as Northumbria in 633, defeat the local ruler Edwin and control it for approximately one year. When Cadwallon was killed in battle by Oswald of Northumbria, his successor Cadafael ap Cynfeddw also allied himself with Penda against Northumbria, but thereafter Gwynedd, like the other Welsh kingdoms, was mainly engaged in defensive warfare against the growing power of Mercia. Powys as the easternmost of the major kingdoms of Wales came under the most pressure from the English in Cheshire, Shropshire and Herefordshire. This kingdom originally extended east into areas now in England, and its ancient capital, Pengwern, has been variously identified as modern Shrewsbury or a site north of Baschurch. These areas were lost to the kingdom of Mercia. The construction of the earthwork known as Offa's Dyke (usually attributed to Offa, King of Mercia in the 8th century) may have marked an agreed border. For a single man to rule the whole country during this period was rare. This is often ascribed to the inheritance system practised in Wales. All sons received an equal share of their father's property (including illegitimate sons), resulting in the division of territories. However, the Welsh laws prescribe this system of division for land in general, not for kingdoms, where there is provision for an edling (or heir) to the kingdom to be chosen, usually by the king. Any son, legitimate or illegitimate, could be chosen as edling and there were frequently disappointed candidates