"According to the Documentary hypothesis, the Biblical claims for the Mosaic authorship of the Pentateuch are false. Rather, the first five books of the Bible are made up of many fragments by different authors. The earliest, the Jahwist (J), was an unknown writer who lived in the Southern Kingdom of Judah in about 850 B.C., either 440 or 600 years after the time of Moses, depending upon one's dating of the Exodus. The Elohist (E) was supposed to have been an unknown writer in the Northern Kingdom of Israel who lived around 750 B.C. The writings of J and E were combined a hundred years later by an unknown redactor. Then, according to this hypothesis, in 621 B.C., the Deuteronomic writer (D) composed the book of Deuteronomy during the reforms of King Josiah. Finally, in about 570 B.C., the Priestly writer (P) wrote various sections of the Pentateuch concerned with genealogical lists and the details of the sacrificial system. These views, which were advocated by Julius Wellhausen, gained a strong foothold in the field of Biblical studies during the twentieth century, despite the fact that both the Pentateuch and many other parts of the Bible specifically state that Moses wrote the Pentateuch. However, there is abundant evidence disconfirming the Documentary hypothesis."
Read More about Biblical Criticism