There are way too many both long forgotten and utterly destroyed past civilizations of old to discount the existence of the Anunnaki at least. Someone or something was creating a whole slew of “overnight” civilizations for many thousands of years all over the Earth, even in Antarctica before it froze over and became the Antarctica we know today. Someone or something not only created those “overnight” civilizations but outright destroyed them so completely that there is nary any physical evidence of most of them today.
Some of these ancient civilizations are only known to have existed by totaled ruined ruins and them being still majorly hot to this very day. By “hot” I mean radioactive. There are at least three major former Indian cities in northern India that got nuked out of existence. They’re still hot to this very day because of how overwhelmingly powerful the nuclear weapons used back then.