Charles Ellicott Commentary Numbers 13:6

"Of the tribe of Judah, Caleb the son of Jephunneh." — Numbers 13:6 (ASV)

Caleb the son of Jephunneh.— In three places—namely, in Numbers 32:12; in Joshua 14:6; and in Joshua 14:14—Caleb is described as the Kenezite (or rather, the Kenizzite). Now in Genesis 15:19 the Kenizzites are mentioned as one of the Canaanite tribes, and in Genesis 36:11; Genesis 36:15, Kenaz occurs as an Edomite name. It has been conjectured from these facts, but, it would seem, on insufficient grounds, that Caleb was of foreign origin and that he had been incorporated into the tribe of Judah.