All these were numbered in the days of Joathan king of Juda, and in the days of Jeroboam king of Israel.

All these were registered by genealogy in the days of Jotham king of Judah, and in the days of Jeroboam king of Israel.

all of them reckoned themselves by genealogy in the days of Jotham king of Judah, and in the days of Jeroboam king of Israel.

All these were listed under the names of their families, in the time of Jotham, king of Judah, and in the time of Jeroboam, king of Israel.

All these were numbered in the days of Jotham, the king of Judah, and in the days of Jeroboam, the king of Israel:

The writer refers here to two registrations, one made under the authority of Jeroboam II when he was king and Israel flourishing, the other made under the authority of Jotham, king of Judah, during the troublous time which followed on the great invasion of Tiglath-pileser. There is nothing surprising in a king of Judah having exercised a species of lordship over the trans-Jordanic territory at this period.

All these were reckoned by genealogies,.... All before mentioned:
in the days of Jotham king of Judah, and in the days of Jeroboam king of Israel; not that those two kings reigned at the same time, and one and the same reckoning is meant; but, as Dr. Lightfoot (y) observes, there were two reckonings; his words are,"in the days of Jotham there was an account taken of the families of Reuben, Gad, and half Manasseh, 1-Chronicles 5:17 and so had there been in the days of Jeroboam the second; then at their restoring by Jeroboam out of the hands of Hamath and Syria, and now at their arming against the Assyrian, under whom they fell in the time of Pekah, and are never again restored to Israel.''
(y) Works, vol. 1. p. 100.

All these were reckoned . . . in the days of Jotham--His long reign and freedom from foreign wars as well as intestine troubles were favorable for taking a census of the people.
and in the days of Jeroboam--the second of that name.

"And these (כּלּם, all the families of Gad, not merely those mentioned in 1-Chronicles 5:13.) were registered in the days of Jotham king of Judah, and in the days of Jeroboam king of Israel." These two kings did not reign contemporaneously, for Jotham ascended the throne in Judah twenty-five years after the death of Jeroboam of Israel. Here, therefore, two different registrations must be referred to, and that carried on under Jotham is mentioned first, because Judah had the legitimate kingship. That set on foot by Jeroboam was probably undertaken after that king had restored all the ancient boundaries of the kingdom of Israel, 2-Kings 14:25. King Jotham of Judah could prepare a register of the Gadites only if a part of the trans-Jordanic tribes had come temporarily under his dominion. As to any such event, indeed, we have no accurate information, but the thing in itself is not unlikely. For as the death of Jeroboam II was followed by complete anarchy in the kingdom of the ten tribes, and one ruler overthrew the other, until at last Pekah succeeded in holding the crown for ten years, while in Judah until Pekah ascended the throne of Israel Uzziah reigned, and raised his kingdom to greater power and prosperity, the southern part of the trans-Jordanic land might very well have come for a time under the sway of Judah. At such a time Jotham may have carried out an assessment and registration of the Gadites, until his contemporary Pekah succeeded, with the help of the Syrian king Rezin, in taking from the king of Judah the dominion over Gilead, and in humbling the kingdom of Judah in the reign of Ahaz.