Roman law is the legal system of ancient Rome. As use in the West the term commonly refers to legal developments prior to the Roman/Byzantine state's adopting Greek as its official language in the 7th century. As such the development of Roman law covers more than one thousand years from the law of the Twelve Tables (from 449 BC) to the Corpus Juris Civilis of Emperor Justinian I (around 530). Roman law, as preserved in Justinian's codes, became the basis of legal practice in the Byzantine Empire and—later—in continental Europe as well as in Ethiopia.