During the earliest years of the Anglo-Saxon rule in England, the word "ætheling" was probably used to denote any person of noble birth. Its use was soon restricted to members of a royal family. The prefix "æþel-" formed part of the name of several Anglo-Saxon kings, for instance Æthelberht of Kent, Æthelwulf of Wessex and Æthelred of Wessex, and was used to indicate their noble birth. According to a document which probably dates from the 10th century, the weregild of an ætheling was fixed at 15,000 thrymsas, or 11,250 shillings, which was equal to that of an archbishop and one-half of that of a king.