The origin of the Israelite (Omride) state is a long-standing question. The fact the first fortifications (Hazor X, Gezer VIII, Jezreel Enclosure) and palaces (Megiddo VA) of this state appear fully formed and with a relatively short period between the origin of the relevant state and the construction of the relevant monuments is, perhaps, the most amazing thing about the Omride state. It should be noted that there was not a single fortified city in all (ancient) Israel known to archaeology between the fall of Iron I Gibeon and the rise of Samaria Building Period I. The question is: how did such a magnificent state manage to arise in only a few decades?
We must first remember that Israel, unlike poorer Judah, had hundreds upon hundreds of oil and wine producing settlements. If it could be conquered, it could, in theory and in practice, provide a sizeable amount of revenue for the conqueror’s forces. Exports most likely went to Egypt. We must also remember that, during the Late Bronze IIa, Labayu, ruling from the possibly unfortified city of Shechem, nearly managed to take Megiddo, and did take over the Dothan Valley. Omri could, with a relatively small force, done the same thing. With a starting territory of the hill country around Tirzah (not securely identified), one of the only Hill Country cities, he could have easily expanded into the Jezreel Valley and foothills of Tulkarm, gaining new territory from which to take conscripts. After this, he likely unified the nation by constructing the elaborate acropolis of Samaria, no doubt being influenced by his Aramean precedents at Gozan. After this unification, he likely had no problem conscripting an army which, without a single large city to oppose it, could go as far as Hazor and Gezer.