From its earliest years, the Crovan dynasty forged alliances with the northern Welsh rulers of the Kingdom of Gwynedd. Some of the earliest evidence of Rǫgnvaldr's kingship concerns his involvement in northern Wales. During the late twelfth century, the region was wracked by vicious interdynastic warring. In 1190, one of Gruffudd's grandsons, Rhodri ab Owain Gwynedd, was ejected from Anglesey apparently by the sons of his own brother, Cynan ab Owain Gwynedd. The thirteenth- and fourteenth-century texts "Brenhinedd y Saesson" and "Brut y Tywysogyon" reveal that Rǫgnvaldr militarily supported Rhodri in his successful re-acquisition of Anglesey three years later. Another mediaeval Welsh text, the fourteenth-century "O Oes Gwrtheyrn Gwrtheneu", refers to the year 1193 as "" ("the summer of the Gaels"), which could further evince the participation of Rǫgnvaldr and his troops.