IT HAS BEEN WIDELY ASSUMED THAT THE DESCENDANTS OF ZERAH, son of Judah (and probably also the descendants of Shelah) migrated to Ireland before the Exodus, because after that, it is said, they disappeared entirely from the Bible story (see Bible Research Handbook Ser. 109h). Thus in the Genealogy of the House of David, published by the BIWF, a daughter of Zedekiah is said to have married a descendant of Zerah in Ireland.
In refutation, it is only necessary to point out that:
1) A census of the tribes present in the wilderness taken shortly before the Israelites entered Canaan, says that “the sons of Judah after their families were: of Shelah, the family of Shelanites: of Pharez, the family of Pharzites: of Zerah, the family of Zarhites” (Numbers 26:20).
2) Achan, well known as the one who stole the loot at Jericho, was a zarhite, “For Achan–-the son of Zerah, of the tribe of Judah, took the accursed thing” (Josh. 7:1, cf. 7:16‑18). Again 1 Chron. 2:7 names Achar (Achan), son of Carmi, as the troubler of Israel, among the descendants of Zerah. 1
3) Individual Zarhites are named in 1 Chronicles 27, verses 8, 11 and 13, as in the time of David.
4) 1 Chronicles 9 records that representatives of all three sections of Judah dwelt in Jerusalem after the captivity, namely the children of Pharez (v.4), the Shilonites (v.5), and the sons of Zerah (v.6). See also Nehemiah 11:5 and 11:24