1 Chronicles 12:1–40 contains material that has no parallels in Samuel or the rest of the Old Testament, and it is assumed that the Chronicler has drawn on a source that he alone had access to, perhaps an untitled military document from the period of the united monarchy.
This section neatly divides into two basic sections:
Early tribal support for David (before his enthronement; 1 Chronicles 12:1–22)
Later tribal support (after his enthronement at Hebron; 1 Chronicles 12:23–40).
Statements emphasizing this support introduce each of the subsections in the first section (1 Chronicles 12:1, 1 Chronicles 12:8, 1 Chronicles 12:16, 1 Chronicles 12:19) and close off the first section as a whole (1 Chronicles 12:22).1 The same vocabulary introduces the second main section (1 Chronicles 12:23), which then shifts to the theme of support for his kingship at Hebron, bringing closure to the account of David’s enthronement that began at 1 Chronicles 11:1.2
1 Now these are the men who came to David at Ziklag, while he could not move about freely because of Saul the son of Kish. And they were among the mighty men who helped him in war.