Penda of Mercia
Cadafael's reign was a critical time for the future of the "Cymry" (i.e., the Welsh and the Brythonic 'Men of the North' taken together, exclusive of all others). There was an alliance of the "Cymry" with Penda of Mercia initially forged by Cadwallon ap Cadfan, and there was ongoing warfare against the then-ascendant Kingdom of Northumbria.