From ancient Sumeria to Egypt and other civilizations in world it is carved in their sacred monuments that we are visited by some of alien species in the past of earth and that they left the mark on humans like new knowledge about various development techniques in many fields.
Annunakis are one of most commented in the circle of ufologists and other that doing reserch in that field.
There are conspiracy theories about them that they are reptilian aliens who enslaved humans in past for digging a gold, and they turn that gold in liquid to run their planet Nibiru trough space gold was a fuel for them and precious source of energy.
Theorist going far as this, they convincing masses of people that reptilians enslaving humanity even today from shadow and secretly.
But I think that if they visited earth in past they have credit for our development most of it. We’d still hide in caves and hunt with primitive tools today.
So do not take any theory easy for truthful because there are some delusory.
4RayMan 