When did city-state unite in ancient Greece?

After the dark ages, herding and farming sprang up again. Soon, borders of areas became fixed, each area became independent by 800 BC. There were forts on hilltops for protection, and a polis grew up around each one. The polis was the center of Greek community life. (The plural of Polis is Poleis.) People were Hellenes, or Greeks. Hellas was their Word for Greece. There were two main city states: Sparta and Athens.