I don't know a great deal about the Sumerian civilisation, but I do know that it was one of the first great civilisations. I gather that Zechariah Sitchin, in his ancient aliens book series, explores the relationship between Sumer and his ancient astronaut theory, which has made me interested in reading what he has to say.

I wonder if the Sumerians were very spiritually-advanced - like the people of Atlantis and Lemuria were said to be.