It is wise to start with Roman law. Roman law is the legal system of ancient Rome, and the legal developments which occurred before the 7th century AD - when the Roman and Byzantine state adopted Greek as the language of the Empire. Laws before the Roman Empire were primarily based on centuries of customs which means that laws were not written. Roman law through its development carries more than a thousand years of jurisprudence. Roman legal history is framed by two codifications, the Twelve Tables and the Corpus Juris Civilis. Roman law, was effective in the Eastern Roman Empire (331-1453), and is also the basis of our legal system, civil system which most countries apply, from Europe to Latin America. Even English and North American Common law also were influenced by Roman law, particularly in the legal glossary - stare decisis, culpa in contrahendo, pacta sunt servanda.
The primary document that all Roman laws were included was the Twelve Tables. This attempt was the earliest of Romans to create a Code of Law and is also the earliest (surviving) piece of literature coming from the Romans. That time Roman Empire was struggling for legal and social protection between the privileged, the rich and elite and plebeians. For this reason a commission was appointed to draft a code of law which would be binding on both parties and which the magistrates would have to enforce impartially.
Twelve tables introduced the system of systematic and procedural study of law, dividing the