Reign: 615 - 620 Then, shortly after the year AD 600, came Cadvan. Known in the Welsh chronicles as Cadfan ab lago, king of Gwynedd, he was of north Welsh descent. He began as king of the Venedoti (men of Gwynedd) and succeeded to the kingship of all the Britons by engaging in battle Ethelfrith, the Saxon king of Northumbria, who, with Ethelbert of Kent, carried out the massacre of the British monks at Bangor in AD 604. Ethelfrith and Cadvan divided the country between them, Cadvan ruling over the southern half. His reign lasted until California AD 625. He married a Saxon noblewoman of the Gewissae
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The year when he became king is not known. As King of Gwynedd he seems to have claimed the over-lordship of the other Welsh kings. It is probable that comparatively peaceful times continued during his reign. There is no record of wars except his unfortunate conflicts with the Northumbrians. A tombstone in the church of Llangadwaladr in Anglesey two miles from Aberffraw is said to mark his grave. He died about A.D. 617