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 (Old English), and written in Old English since circa 600, beginning with the Law of Æthelberht. Following the Norman invasion of England in 1066, Anglo-Norman French became the official language of legal proceedings in England for a period of nearly 300 years until the Pleading in English Act 1362 (and continued in minor use for another 300 years), while Medieval Latin was used for written records for over 650 years. Some English technical terms were retained, however (see Anglo-Saxon law: Language and dialect for details).