Pulu wrested the throne of Ashur in 745 BC, from a "Shalmaneser V" whom Pulu's family then disavowed. Perhaps similar breaks of memory were had in Israel at the time. So: Carl Lederer, and now youtuber "Dig."
The eretz-Israel had been a united land under Jeroboam II, but as all men do he died. His heir Zechariah was ousted in a coup and that coup - under Shallum - collapsed. Menahem and Pekah picked up the pieces. The Bible says Menahem ruled for ten years and Pekah for twenty.
The maths don't add up under scrutiny from Assyria however. Menahem gave tribute to "Pul"; that emperor claimed he'd had it from Pekah as well. Luckily, we have a local report: from Hosea the northern prophet. His sermons made a point of the twin iniquities of his land. Hosea didn't consider Judah in this calculus, despite that it was starting to matter again; Hosea's twinland was Ephraim-and-Israel.
According to Lederer's reading, Pekah had a base in Gilead and simply slipped over there, keeping that base. The face-saving fiction was that Pekah would hold the title "Shalish" and not "king of Israel". In practice, yeah, Pekah was sulṭan across the water, as it were.
I must inject here that per Rendsburg (pdf), Amos especially Amos 6 is also writ in a nonJehudi Hebrew to be considered northern. Amos didn't preach about Israel/Ephraim's twinship for the simple reason he preached under Jeroboam II when that kingdom was one. His kingdom likely included Judah then; maybe then Edom (so I'm not getting into which "Tekoa" here). So for Amos, Jeroboam's court was the court which mattered.
Pekah would eventually switch to being an ally of Damascus and make a bid to take Judah. Ahaz squealed to Assyria who then attacked and got all of it. Israel, from Samaria, would end up a rump and tributary Assyrian vassal, under Hoshea.
