How did the structure change over time in ancient Greece?

In the archaic period, also called the Mycenaean period, Greece was a series of small kingdoms, or cheifdoms, where heavily fortified citadels dominated small provinces of land. Each citadel had a king, or chief. There seems to have been a dominant chiefdom at Mycenae, and the kind of chief of Mycenae had some preeminence over the other kings.