Judah only. See note on "one tribe" (1 Kings 11:32).
Related Commentaries of 1 Kings 12:20
1 Kings 12:20
20 And it came to pass, when all Israel heard that Jeroboam was come again, that they sent and called him unto the congregation, and made him king over all Israel: there was none that followed the house of David, but the tribe of Judah only.