Charles Ellicott Commentary 2 Kings 10:33

"from the Jordan eastward, all the land of Gilead, the Gadites, and the Reubenites, and the Manassites, from Aroer, which is by the valley of the Arnon, even Gilead and Bashan." — 2 Kings 10:33 (ASV)

From Jordan eastward. — This verse defines the borderland that Hazael ravaged and, in fact, occupied. It was the land east of the Jordan, that is, all the land of Gilead, which was the territory of Reuben, Gad, and the half-tribe of Manasseh.

From Aroer. — Aroer, now ‘Arâ‘îr, on the Arnon, was the southern limit of Gilead, which extended northward to Mount Hermon, and included Bashan. Even (both) Gilead and Bashan, is added to make it clear that the whole of the land east of the Jordan, and not merely Gilead in the narrower sense, was conquered by Hazael. These conquests of Hazael were characterized by great barbarity. (Compare to Amos 1:3-5, and Elisha’s prediction of the same, 2 Kings 8:12, supra.)

Ewald thinks Hazael took advantage of the internal troubles at the outset of the reign to effect his conquests. But a man of Jehu’s energy must soon have established domestic tranquillity.