Well, let's say that I am a ruler and I control this territory right over here. And either through my charisma, my military tactics, maybe I have a new weapon, some political intrigue, some weak neighbors, I'm able to conquer some more territory right over here. What does that do for me? As I expand, this gives me more land and more people to rule over. And I can tax that land and people to have more wealth and larger armies. And so these two things are pretty good ingredients to be able to take on even more of my neighbors and expand even further. And so you might say, well, why doesn't that process just keep on going on indefinitely?