Many of the books in the Old Testament were written between 1200 and 100 BC in Hebrew, the language of the people of Israel. From the sixth century BC onwards, Aramaic became increasingly common. Some parts of the Old Testament were written in this language, the main language spoken in the Holy Land during the time of Jesus.
Between 300 and 100 BC, the Scriptures were translated into Greek (this translation is called the Septuagint), because during this time Greek was spoken more frequently than Hebrew. The New Testament was written in Greek.