A. One was from Judah and one from Joseph—echoing the twofold Messianic hope (Messiah ben David and Messiah ben Joseph).
B. One was Jewish and one Gentile.
C. They were two witnesses who stood at the threshold of a new era for Israel.
B appears to be the strongest possibility.
Joshua was from the tribe of Ephraim, while Caleb is called “the Kenizzite” (Numbers 32:12; Joshua 14:6, 14). Because the Kenizzites are listed among non-Israelite peoples, and because the name Kenaz appears in Edomite genealogies, some scholars suggest that Caleb may have had a non-Israelite origin (Milgrom, JPS Torah Commentary).
Others understand Caleb as fully Israelite, seeing “Kenizzite” as a clan-name within Judah or as descent from a man named Kenaz (Rashi). Still others suggest that Caleb was an outsider who became fully joined to Israel.
The evidence may lean toward Caleb having roots outside Israel, yet being fully accepted among the people of God and receiving an inheritance in Judah. The picture is striking: Joshua and Caleb entered the land together, and many see in this a beautiful foreshadowing of the unity of Jews and Gentiles brought together for God’s purposes.
Note as well that in the Millennium, we read in Ezekiel 47:21-23 that Gentiles will also possess (inherit) land within the tribes and shall be considered native-born children of Israel. Perhaps Caleb foreshadows this great millennial event.