The rise and fall of societies in prehistoric Greece
The Ancient Greeks who presaged our philosophies, political systems, and arts emerged in a land that had already been settled by mankind for tens of thousands of years. Despite what some of them believed the Greeks were not been born out of the Earth, but rather from the ashes of earlier societies. In Greece's prehistory - the time before writing - entire societies, including palatial kingdoms and petty warlord states, and been born, grown to upredecedented heights, and collapsed.
Prehistory is the time before writing. Without writing there is no first hand evidence of history's narrative. There is no one telling us why change occurred or what life was like. Evidence is limited to silent artefacts. The prehistory of Greece begins with the very first hunter gatherers and ends with the recorded epic poems of Homer and Hesiod around 800BCE.
Neolithic Greece
In the far past change was slow, the pace of development indiscernible and its forces so subtle as to be unseen. Since 35,000BCE the most recent Ice Age had been subsiding (with some interruptions), and as temperatures warmed lands around the world became richer, and life, relatively speaking, easier. This increase in population would have continued at its glacial rate and finally plateaued but for an unprecedented invention around 9500BCE in the near east: agriculture. The gulf between pre- and post-agricultural life was immense: agriculture inducted the Neolithic revolution, which witnessed populations explode, crops and animals domesticated, and pressure to form concentrated communities. People were forced to cooperate, and the possibility of surpluses introduced wealth and luxuries.
The slow warming of those thousands of years could only have been noticed by a strong inter-generational memory; without writing life appeared unchanged. Nonetheless the neolithic revolution reached Greece by 7000BCE, and the hunter-gathering culture was repalced by a farming culture1. Year-to-year innovation was non-existent, aside from brief flashes that redefined the Greek societies: A thousand years later and the Greeks had pottery, another three thousand and they had plows.
Bronze Age Greece
The beginnings of Bronze Age Greece (3000BCE) saw an increase in wealth, made possible by larger populations and new technologies, especially the plow. With the increased wealth came inequalities, and inequalities spurred their own changes: Some communities began to build fortifications and ritualize the collection of luxuries.
Mainland collapse
The bronze age Greeks were primitive compared with the great civilizations in the near east - Egypt had already been unified under a pharoah and an urban culture was beginning to coalesce in the Sumerian city states. The Greeks were left even further behind their near eastern peers as their socieites crumbled. Between 2300-2000BCE something unknown hit the Greeks, hard. What ever the cause - and it remains unknown - it caused irreversible damage. As accumulated wealth was lost, life became desperate, leaving records of itself only in the remains of burned fortifications all across the peninsula. As settlements were reduced and trade ceased, mainland Greece entered its first dark age.
Rise of the Minoans
But while culture on the mainland was crumbling, on the island of Crete society continued to flourish: the Minoan civilization. The Minoans continued to produce artworks and pottery, and had a writing script called Linear A (which incidentally has never been deciphered). Their societies were based around administrative palaces with centralized command economies: produce was brought into the palaces, taxed, and then redistributed.
Rise of the Mycanaeans
As the Minoan civilization continued to thrive on Crete, protected by the surrounding ocean, a new culture was developing on the mainland. By 1700BCE a new age had begun: Mycenaean Greece. Once again there was a concentration of power and wealth, fortifications were built and valuables collected. The powerful leaders of this age were warlords, and the art of this new culture displayed its interest in martial power and violence. They also developed a writing script, based on on the characters of Linear A: (imaginatively named) Linear B (which has been deciphered).
Between 1600BCE and 1400BCE something strange (from our distant perspective) happened: At the beginning of this time the Minoans were the master civilization, and their goods and culture overshadowed the mainland Mycenaeans. But by the end of this period Minoan culture had collapsed, so much so that their writing was replaced by that of the mainlanders. A large volcanic eruption around this time could be responsible. It might have reduced the wealth of the Minoans sufficiently to destablize the palace centers, and with them, sent the Minoan command economy into a downward spiral.
The Dark Age
The great Greek dark ages were brought on by a major disintegration of the ancient world, called the Bronze Age collapse. Between 1225-1175 the entire ancient world edged and tipped into disaster. At the same time the great palaces that had been built by the Mycenaeans were burned down, and large populations were displaced, sending refugee-like armies swarming across the ancient world. Even the mighty Ugarit and Hittite empires fell, while the Egyptians struggled against the maraudering armies and lost large swaths of their kingdom.
In Greece writing disappeared, art dwindled, populations shrunk, and societies regressed.
Iron Age Greece
In Greece the beginnings of the Iron Age coincided (incidentally) with the dark ages. Between 1300 and 1000BCE the population of Greece was reduced to a third, and undoubtedly life was wretched. Yet all around were seemingly godlike ruins of the former Mycanaeans. The far past seemed like a magical time compared to contemporary life in the dark age. As a result, the Greek culture formed rich mythologies that looked back to a golden age and inspired tales of a heroic past.
Various forces intersected to bring an end to the dark ages: in the Levant the Phoenicians began to ply their merchant trade throughout the entire Mediterranean Sea, richening the entire region in a joint economy. More generally, the ninth century (BCE) witnessed a renaissance across the ancient world. The change in global climate made the Mediterranean basin more fertile, and made a population boom possible once more.
Homer and the end of Greek prehistory
History as change is about critical mass. All the necessary pieces came together in the eighth century to set things moving for the next millennia: growing populations, improving technologies, long distance trade, establishment of laws and social orders, and perhaps most importantly, the invention of the Greek alphabet. The writings of Homer and Hesiod formed a backdrop against which these changes could express themselves, and in themselves, instantiated a new durability for knowledge. With writing knowledge could outlast a person's lifetime, and the stories that form history could begin accumulate. Societies could still rise and fall, but never again (not yet anyway) would they be so decimated as to lose their sense of where they'd come from.
1 Some people suspect that the farming proto-Indoeuropeans (the culture that spoke the root language that defines the bulk of Eurasia) may have spread into Europe (including Greece) at this time.
References: Wikipedia and the highly recommended book: The Greeks by Ian Morris and Barry B Powell