And this map right over here, this is the Persian Empire in 500 BCE under Darius the Great. It's near its maximum extent. And it's a pretty incredible empire. It's worth noting, it's big by any stretch of the imagination. But it's, at this time, the population is on the order of 50 million people. And based on the accounts that I've seen, that's almost half of the world population at that time. No empire in history, as far as we can tell, has ever had such a large fraction of the world's population under its control.