There are differing theories about what caused the collapse of Mycenaean civilization, one of the most common being that the Dorians, a ‘barbarian’ people (though it is often told that the word ‘barbarian’ in ancient Greek simply meant non-Greek speakers) descended from the north and devastated the culture they found, which set in motion a socalled ‘Dark Age’. Another theory asserts that a people referred to as the ‘Sea Peoples’, probably from southwestern Anatolia, raided the mainland culture during the course of several decades (the Dorians, that is to say, not being the only cause of the Mycenaean collapse).
Yet a third position, held by some modern archaeologists, is that ‘enemy invaders’were not responsible for the collapse of the Mycenaean world, but simply changes in patterns of trade.
It seems well established, however, that some very aggressive northern tribes did in fact move down from the Pindos mountains, wreaking havoc as they went, and inspiring the building of defensive fortifications at Mycenae, Tiryns, and the stairway to the spring below the Acropolis, all of them seen as major military engineering feats. With the first wave of attacks, Pylos was destroyed (1200 BC), then Mycenae and Tiryns, and both lay in ruins by 1150 BC. Athens & Attika survived because the Dorians went around it perhaps looking for more fertile soil or more lebenshraum since Attika is bordered by the sea on three sides and not a huge place.