Comment of the Day: Musings on... the Loyal-Spirit Great Kings of Iran 550-330 BCE...: "'I do not think we understand very well why...:
...a Kurush could do what a Ramses, an Ashurbanipal, a Sargon, or even a Nebuchadnezzar could not.' Is there SUCH a mystery here? My take on this (and similar phenomena like Alexander, the Islamic expansion, and the Mongols) is that they can occur at a certain point in history when semi-states have been created, but not yet nations with all the 'patriotism' and mythology that implies.
Under these circumstances, growing an empire is basically a sequence of hostile takeovers; all it requires is decapitating a few flunkies at the top and replacing them with your flunkies. It really IS the equivalent of RJR taking over Nabisco. And just like RJR taking over Nabisco, everyone but the C-suite doesn't especially care about what has happened --- like will go on as before, neither worse nor better.
Note what this suggests --- that this type of empire building is easy'ish.
Doing it earlier (before there exists a state apparatus you can take over) is much harder. Think ancient history like Ramses, Ashurbanipal, Sargon, who have to create their own states. (Or a few modern examples like the US and Russia, where the dynamics are completely different because of the power imbalances.)
Doing it later is likewise harder because the states now fight back seriously, not just the flunkies at the top, but the entire nation. Think Napoleon or Hitler.