Jamieson, Fausset and Brown on 2 Chronicles 8:3-6

3-6. And Solomon went to Hamath-zobah--Hamath was on the Orontes, in Coele-Syria. Its king, Toi, had been the ally of David; but from the combination, Hamath and Zobah, it would appear that some revolution had taken place which led to the union of these two petty kingdoms of Syria into one. For what cause the resentment of Solomon was provoked against it, we are not informed, but he sent an armed force which reduced it. He made himself master also of Tadmor, the famous Palmyra in the same region. Various other cities along the frontiers of his extended dominions he repaired and fitted up, either to serve as store-places for the furtherance of his commercial enterprises, or to secure his kingdom from foreign invasion (see on 2Ch 1:14; 1Ki 9:15).

2Ch 8:7-11. The Canaanites Made Tributaries.