The history of Herefordshire starts with a shire in the time of Athelstan (895–939), and Herefordshire is mentioned in the Anglo-Saxon Chronicle in 1051. The first Anglo-Saxon settlers, the Magonsætan, were a sub-tribal unit of the Hwicce who occupied the Severn valley. The Magonsætan were said to be in the intervening lands between the Rivers Wye and Severn. The undulating hills of marl clay were surrounded by the Welsh mountains to the west; the Malvern Hills to the east; the Clent Hills of the Shropshire borders to the north, and the indeterminate extent of the Forest of Dean to the south. The shire name first recorded in the Anglo-Saxon Chronicle was derived from "Here-ford", Old English for "Army crossing", the location for the city. The area was covered first by Offa of Mercia, who constructed the dyke as a boundary to keep warring tribes out of the Mercian kingdom: an early indication of the ambivalent relations with the Welsh. The shire as an administrative unit was developed from Alfred the Great's Burghal Hidage, and the Shire-reeve courts of the Hundred. In 676, during the reign of King Æthelred of Mercia the Archbishop of Canterbury Saint Theodore of Tarsus founded the Diocese of Hereford, to minister to the minor sub-kingdom of Magonsaete, and he appointed Putta as the first Bishop of Hereford. The establishment of a centre of law and justice was supported by a monastic chapter that flourished during the Tenth century Reformation. Hereford's geographical location at the hub of the shire allowed Anglo-Saxon ealdormen to manage affairs; and Hereford played a vital role in the Scandinavian wars until Ralph, Earl Hereford was deposed by the regal Earl Harold Godwinson. In the feudal Domesday Survey some adjacent areas of the Welsh Marches are assessed under Herefordshire. The western and southern borders remained debatable ground ("Archenfield") until, with the incorporation of the Welsh Marches in 1535, considerable territory was annexed to Herefordshire. These areas formed the hundreds of Wigmore, Ewyas Lacy and Huntington, while Ewyas Harold was subsumed into Webtree Hundred. At the time of the Domesday Survey the divisions of the county were very unsettled. As many as nineteen hundreds are mentioned, but these were of varying extent, some containing only one manor, some from twenty to thirty. Of the twelve modern hundreds, only Greytree, Radlow, Stretford, Wolphy and Wormelow retained their original Domesday names. The others were Broxash, Ewyas-Lacy,