Mu is the name of a supposed ancient
advanced civilization that existed 78,000 years ago in the
Southern Pacific. It lasted many thousands of years and eventually was sunk by large
earthquakes. They were, of course, well
advanced beyond our current civilization and may well have been
populated by
aliens. Written about at length by
James Churchward in his series of five books written in the 1920's and 30's.
Sometimes considered to be the same as
Lemuria.