Every 3 or 4 generations after the previous Empire falls, the next starts to rise. It's happened often enough that some historian is trying to get a natural law named after themselves.

Starting an empire, given the right conditions, is easy. You need a small, well armed, and focused polity; a couple of systems and a strong religion normaly does it, although a burning need to bring 'peace' or 'justice' has also worked.

And 'well armed' doesn't always mean millitray might, although that is considered the easy path. Fierce debating skills, a solid traiding tradition, once even a strong sense of empathy have all started empires.