The Isle, which contains the whole of the fenland forming this northern half of Cambridgeshire, is far older as a political entity than the southern part of the county. Its existence dates back to the far-off days of the Anglo-Saxon conquest, in the fifth and sixth centuries, when the poor remnants of the British population in East Anglia, once the proud tribe of "the great Iceni," fled for refuge into the "dismal swamp" of the Fens. Here they held out for centuries, and formed themselves into a new tribe, the Girvii (as our earliest Latin chronicler transliterates the Welsh name Gyrwy, signifying "brave men," by which they called themselves). This Girvian principality has ever since held together. It passed as a whole into the hands of St. Etheldreda, by her marriage (in 652 A.D.) with the last Girvian Prince, Tonbert, and from her to her successors the Abbots and Bishops of Ely, whose jurisdiction survived until the nineteenth century. Meanwhile the old southland homes of the unhappy Britons were being shared up by their English exterminators. The East Anglians swarmed over the uplands to the east, and joined hands (not in friendship) with the more powerful Mercians swarming in from the west. Roughly speaking the Cam divided these jarring tribes, which lived in undying hostility till the various English Kingdoms were united into one (in A.D. 827) by the genius and valour of Egbert, the first "King of the English." But the boundaries were not effaced till the desolating flood of the Danish invasions poured over all. When that flood was stayed by Egbert's glorious grandson, Alfred the Great, and the district once more made English and Christian by his only less glorious son, Edward "the Elder," it was formed by him into a County called, from its chief town, Cambridgeshire (or, as it was then, "Granta-bryg-shire"). This was in the year 921. But for the first idea of any union between this new County and the old Isle of Ely we must wait another two centuries, when, in 1107, the Abbot of Ely became a Bishop, with the Isle and the County together for his See. The ecclesiastical tie thus formed has gradually developed into a civil tie also; just as the first union of the English race under a common Primate, the Archbishop of Canterbury, paved the way for its union under a common King.