The Iron Age Greek migrations were effected by a population of émigrés from amidst the displacements and reconstruction that occurred in Greece proper from the middle of the 11th century to end of the 9th century BCE (the Greek Dark Ages). These movements resulted in the settlement of the Aegean islands, Cyprus, Crete and the western coast of Asia Minor and the founding of new cities which afterwards became centers of the Greek civilization. The migrations were effected in consecutive waves by tribal groupings known as the Aeolic, Ionian, Doric and Achaean (Arcadian) migrations. These movements differed from the Greek colonisation of the Archaic period in that they were more ad hoc affairs instead of the result of a planned process of colonisation on the part of the mother city, and they a