A. Judah. That’s just one tribe you ask? First of all Judah was the dominant tribe of the Southern Kingdom which is where most Jews today descend from. We are also named Jew, based on a phrase from the Purim Megillah. Mordechai is called “A Man of Judah” although the same verse traces his lineage to the tribe of Benjamin. The Talmud solves this problem by saying that those who deny idolatry (as Mordechai valiantly did, refusing to bow to Haman) and dedicate themselves valiantly to belief in G-d (related to the root word of Judah) are called “Yehudi” (of Judah). Yehudi is Hebrew, Yid is Yiddish, and Jew is English.