Where does the Dorians fit in on this? There was a History Channel Special on the Sea Peoples a while back. It put out the theory that the Sea Peoples were a mix bag of uprooted peoples that started with the Dorian migration to the Peloponnese.
Since the Mycenaeans used Linear B to record the Greek language, there was no Dorian invasion at that time.
Linear B was derived from Linear A, which suggests that earlier on, the ancestors to the Greeks came in from somewhere, or had a sudden population explosion, perhaps as an exploited people. An analogous (and later) situation would be that of the slavery imposed by the Spartans in the Peloponnese. The population of the Spartan master race declined over a few centuries, while the population held in thrall (and therefore, not feeding its children to the sword) increased in size. The Battle of Leuctra saw the Spartans unable to field even 1000 citizen troops; its army was annihilated by that of Thebes (the real winner of the Peloponnesian War), and the Theban army then marched hither and yon around former Spartan territory and built walled towns to hold the former slaves of the Spartans.