The story of Moses leading the Israelites is found in the Book of Exodus, which is considered to be part of the Deuteronomic History. This was written down by an anonymous author now known as the Deuteronomist during the seventh-century-BCE reign of King Josiah of Judah. Although written down more or less in the form we know today by the Deuteronomist, there was undoubtedly an earlier written or oral source that the Deuteronomist relied on.

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'Deuteronomist und Jahwist'

We know that the anonymous scribe or scribes known today as the Deuteronomist, or 'D Source', lived in Jerusalem during the reign of King Josiah, and no doubt worked under his instructions when writing the book of Deuteronomy and the Deuteronomic History (Joshua, Judges, Samuel and Kings). We do not know the actual names of the writers.

Among others, Jeremiah, Zephaniah and the Deuteronomist are said to have lived during the reign of King Josiah.

The 'D Source' was, of course, anonymous but is called the 'Deuteronomist' because the Book of Deuteronomy was the source's principal contribution to the Pentateuch.