As said back a wee bit, MU was known about well before 16 TH century, I like how there is much about MU within India's written past and orally huge amounts denoting past history n herstory, here is but one >
http://www.sacred-texts.com/atl/ssm/index.htm >
He claimed that, while posted in India, he befriended a priest ('Rishi'), who revealed to him ancient tablets written in an otherwise unknown language. The Rishi taught Churchward how to read this language, Naacal. The tablets described the land of Mu, the Lemuria of the Theosophists.