The Dorian invasion caused the Late Bronze Age collapse which led to the Greek Dark Ages. Sparta and Athens arose afterward. Sparta was controlled by Dorian-types (comprising Dorians) while Athens was controlled by Athenian-style slave-makers (comprising Athenian slave-makers).
Invasions, destruction and possible population movements during the collapse of the Bronze Age, c. 1200:
Full image: http://i.imgur.com/ma3riJi.png
The sinking of Atlantis is typically a reference to the Late Bronze Age collapse: