 According to the "Liber Landavensis", when King Tewdrig fell in battle against the Anglo-Saxons at the River Wye, it was his desire to be buried on Ynys Echni; however the soldiers were unable to get his body there.Instead, he was buried at Mathern by his son Meurig ap Tewdrig.An oratory was built on top of his grave, and the land surrounding it was given to the Celtic Christian Bishops of Llandaff.