Legal English the history of the development of English as a legal language. In prehistoric Britain, traditional common law was discussed in the vernacular (see Celtic law). The legal language and legal tradition changed with waves of conquerors over the following centuries. Roman Britain (after the conquest beginning in AD 43) followed Roman legal tradition, and its legal language was Latin. Following the Roman departure from Britain circa 410 and the Anglo-Saxon invasion of Britain, the dominant tradition was instead Anglo-Saxon law, which was discussed in the Germanic vernacular (Anglo-Saxon, Old English), and written in Old English since circa 600, beginning with
History of Anglo-Saxon England and their cultural descendants. Anglo-Saxon history thus begins during the period of Sub-Roman Britain following the end of Roman control, and traces the establishment of Anglo-Saxon kingdoms in the 5th and 6th centuries (conventionally identified as seven main kingdoms: Northumbria, Mercia, East Anglia, Essex, Kent, Sussex, and Wessex), their Christianisation during the 7th century, the threat of Viking invasions and Danish settlers, the gradual unification of England under Wessex hegemony during the 9th and 10th centuries, and ending with the Norman conquest of England by William the Conqueror in 1066. Anglo-Saxon identity survived beyond the Norman conquest, came to be