One of the early periods in Greek history has been labeled “The Dark Ages”, because of evidence of a radical change in Greek culture and retrogression to a more primitive state. This period began circa 1200 B.C. and marked the end of the Mycenaean palace culture that had come before. It had first appeared that the Greek Peninsula had been overrun by invaders part of the so called Dorian invasion, but recent archeology has shown that the Mycenaean age was replaced by a new order which was crude in its beginning as evidenced by the low quality of art and technology. Despite this pause in the development of Greek culture, the loss of a sense of central government and the resulting isolation of small Greek communities set the stage for the development of the Polis.
Many of the characteristics of the Dark Ages are known. There was a rapid shift from bronze to iron technology, pictorial representation ended, luxury disappeared, and religion was practically non-existent. After one hundred and fifty years, however, new innovations began to appear around 1050. A new style of pottery, labeled protogeometric, was produced and by 1000 B.C. Greek expansion across the Aegean began. This large scale migration implies an outward-looking vision similar to that of the European explorers during the renaissance.
The Greeks crossed the Aegean and settled in Asia Minor by bands matching the dialects of the Greek language. The map below shows this with yellow designating Aeolic, blue Ionic, and brown Doric.
The reasons for the migration are obvious: attraction to fertile land near the coast and the lack of any powers or population centers that could inhibit the relocation drove the Greeks to Asia in large numbers. We know that three hundred years later Asia Minor was fully populated with Greeks and the Aegean had become the Greek lake, but the process that led to this including battles between the Greeks over the new territory is obscure. Much later the Spartan-led revolt in this new territory would lead to the Persian invasion of Greece.