“The sons of Reuben, the first-born of Israel, were Hanoch, Pallu, Hezron, and Carmi.”
In fact, the real first-born was Reuben, yet he gets very little attention. Reuben (the Reubenites) had 4 sons (1) Hanoch (the Hanochites), (2) Pallu (the Palluites), (3) Hezron (the Hezronites), and (4) Carmi (the Carmites). However, this Hezron is not the same as the one listed as the grandson of Judah, the son of Perez. These names are exactly the same as in Genesis, chapter 46.