The Septuagint is the Greek translation of the Old Testament. The Old Testament was originally written in Hebrew. It was during the reign of Ptolemy Philadelphus (285-246 B.C.) that the Pentateuch, the first five books of the Bible, were translated into Greek. Shortly afterwards the rest of the Old Testament was also translated. This translation was done by approximately 70 translators. Hence, the Septuagint is known by the letters LXX, the Roman numerals for seventy.