The New Testament (Greek: Καινή Διαθήκη, Kainē Diathēkē) is the name given to the final portion of the Christian Bible, written after the Old Testament. It is sometimes called the Greek Testament or Greek Scriptures, or the New Covenant – which is the literal translation of the original Greek. The original texts were written in Koine Greek by various unknown authors after c. AD 45 and before c. AD 140. Its 27 books were gradually collected into a single volume over a period of several centuries. The New Testament is a central element of Christianity, and has played a major role in shaping modern Western culture.