I'm under the impression (although I may be VERY wrong, considering Ancient History is NOT by any means my area of expertise) that the Israelites, whilst proving to be a hardy people, weren't demographically very strong. A tiny population, poorer land and technology. I sorta think of them as a religious-zealot-version of the Samnites. Very good defensively, but hard to see them conquering many lands. A pan-Hebrew power could be a regional power, but with Egypt and Mesopotamia on either side, it's going to be a Poland, not a Russia.