The postmosiaca passages after Mose’s death is the mystery. But most likely added editorials continuing the events that took place after his death.
What about postmosaica passages?
But to say that the composition, even the origins, of the Pentateuch is to be associated with Moses certainly does not mean he wrote every word. Traditional approaches to this question acknowledge that Moses did not write the entirety of the Pentateuch when they point to a so-called postmosaica.
Postmosaica are passages that had to be written after the death of Moses, and of course, the most obvious postmosaica is the account of his death in Deuteronomy 34. There are postmosaica in the book of Genesis as well.
While Ur is an ancient city predating Moses, the reference to Ur of the Chaldeans (see Genesis 11:31) is a postmosaica since the Chaldeans were an Aramaic-speaking tribe that lived in the first millennium BC, long after the death of Moses.
In Genesis 14:14 the narrator reports that Abram chased the four ancient Near Eastern kings who kidnapped Lot “as far as Dan.” This reference to the city of Dan is a postmosaica because this city, earlier called Laish, was not named Dan until the time of the Judges (see Judges 18), and of course the name derived from the tribe of Dan, named after Jacob’s son Dan, Abraham’s great grandson.
* Sorry about the bold lettering. I could not get it back to normal text for some reason.