Maybe for a time. But what happens when they run out of territory to conquer? Or when the territory acquired through conquest becomes to vast to maintain? After Ashurbanipal's reign the Assyrian Empire had swelled to its greatest size. But his successors had trouble claiming the throne because governors like Sin-shumu-lishir, who held nearly equal power in his province of Babylonia, could try to establish their own empires from within. Following this the Assyrian Empire rapidly declined as its extensive borders were attacked on several fronts by the Babylonians, Medes, and Egyptians.