I’m trying to find a definite answer of who the dorians were and where did they come from. I understand they came around the Mycenaean age and conquered the mycenaens from Epirus and around Peloponesse (laconia). They are said to have a unique culture and society. Is it possible these people could have been of Illyrian descent, Epirus was never 100% Greek and I find it odd how a Greek civilization would completely conquer another Greek civilization. Also the helmets of the illyrians also looked very similar to that of the Spartans.
This is a common question here and has been discussed multiple times in the past. It should really be on the FAQ.
But in the meantime, here's a sortable search for previous discussions.