The Lost Continent of Lemuria. Sometimes also called MU.

1. "Lemuria was a continent and a cultural period that predated and overlapped Atlantis. It was located in the Pacific region of Earth and is thought to have been the first culture influenced by extraterrestrial sources." (PoL).

Lemurian Record Keepers were called the snake people, which links them to the Sirians. When Lemuria went down, they fled to south and north America. A lot of the "native" American Indians actually are descendants of the Lemurians.

2. According to Solara, the Lemurians were in contact with several extra-terrestrial civilizations, mainly from Sirius and Arcturus. They also were in touch with the EL's.
Solara, too, mentions links between Lemuria, and Tiahuanaco and the Land of AN.

When Lemuria disappeared into the Ocean, its inhabitants fled. Remains of their civilizations are found in:

3. Other sources mention visits from inhabitants from :