According to Zecharia Sitchin and his interpretation of ancient Sumerian texts, the Anunnaki were extraterrestrials (aka “angels”?), who were an extremely long-lived race, potentially living as long as 500,000 years. Laurence Gardner reduces this to more on the order of 50,000 years, and notes specifically that the Anunnaki were not immortal. Sitchin and Gardner also disagree on the date of the Great Deluge/Flood; Sitchin assuming a time frame of 11,000 B.C.E., while Gardner assumes one of 4,000 B.C.E. {source: planetxrobert}