I've been listening to too much Nirvana.

Why do empires form? I honestly feel that empires stem from the need for space in a rapidly growing society. Once an area becomes successful, its population rises. Everyone knows that once you have a bit of an economy going it's time to start building up the family, right? As populations grew and grew, leaders needed to find a way to accomodate their people. The only solution (other than mass murder or birth control perhaps)? Expansion. As societies expanded to become larger and larger, it was of course necessary to take over surrounding lands. And resulting from this, we find the empire. Just ask the Chinese - expansion was provoked during the Han dynasty when high agricultural production supported rapid growth and prosperity. By the end of the former Han dynasty, the population had tripled. In the case of India, the ruler Ashoka conquered considerable land to the Mauryan Empire. He had encouraged the expansion of agriculture with irrigation systems - obviously the population probably jumped from this. Finally, in terms of Rome, after establishing a stable agricultural economy, the empire expanded all over Europe, Mesopotamia, northern Africa, and even parts of Britain, most likely with the side note that their population was growing. Obviously, I stand by my belief that empires form from the need for space.