Shifts in populations
Toward the end of the 13th century, the mainland palaces were burned, possibly within a short time of each other; the exception was Thebes in the north, which may have received a destructive blow slightly earlier. Mycenae and Tiryns continued to be inhabited and indeed had very rich and energetic periods of pottery production and trade in the 12th century; Pylos was deserted, however, and Athens was inhabited but not wealthy. New centres, both of refuge and of independence, became conspicuous, such as Lefkandi on the inner shore of Euboea, south of Chalcis. The Cyclades, Crete, and, in the west, the Ionian islands such as Cephallenia experienced an increase in population. New expeditions eastward to Cyprus consisted of small groups who fortified military settlements around the coast. Anatolia may also have received new immigrants, as it had periodically since the 15th century, as far as Tarsus in Cilicia.
No completely satisfactory explanation for the collapse of the palace systems and the movements of populations has been found. Perhaps one must look toward a combination of factors such as climatic change and drought, harvest failure, starvation, epidemic, civic unrest, and resentment of palace taxes. Contributing factors may also have been the breaking off of trade with the east after the clash of the Hittites and Egyptians at the Battle of Kadesh earlier in the 13th century, the presence of roving piratical bands of both local peoples and immigrants around the coasts of the eastern Mediterranean (known in the Egyptian records as the Peoples of the Sea) who were hired as temporary allies by several states, and general frictions caused by universally failing economies and alliances. At any rate, the stable states of the wealthy later Bronze Age, which had been bound by commercial exchanges and political alliances, gradually or swiftly collapsed into near chaos. By the end of the following Dark Age (lasting perhaps from 1100 to 1000 in some places, or 900 in others), new peoples had arrived and settled, as, for example, the Dorians in southern Greece and Crete and the southern Cyclades as far as Rhodes or the Phrygians in central Anatolia. Notable too is the fact that new late Hittite states had been formed in northern Syria at this time.