When the Anunnaki colonized Earth they created at least one stargate. The main one seems to have been located at the North Pole. This may have been ethereal, rather than physical. A warping of energies using Earth’s magnetic field. This may have been used to take rare resources from Earth to other places in the universe.
Sometime afterwards, another people came from there and destroyed everything they could. Not only the settlements, but even food sources. They have been called the Aryans or Orions. The Aryans are a very malevolent race controlled by a central Artificial Intelligence. They came as robotic, humanoid forms with fangs, claws, etc.
The Artificial Intelligence gives them instructions in a one-way, autocratic system. Inside each robot is an energetic entity called a Vril. These are like Shadows and may even be immortal. The humans they captured were then used to reinforce their numbers. Their minds were changed and programmed by the Artificial Intelligence.
In human society, many fascist and communist leaders are said to have been part of a modern day Vril Society. If we do create a worldwide Artificial Intelligence, it will become the only authority. We will be like the Vril. When fully fused with this tech, we will be dependent on devouring energy and just like Shadows, be cut from Source.
The Anunnaki became complacent in the millennia they ruled Earth. This attack took them unprepared. The Aryans had gained much ground before the Anunnaki could counter. To consolidate their power, the Anunnaki had shaped themselves as giants. They too used humans for their war. They modified them into much larger versions.
It is unknown how long this war lasted, but the Aryans won. The defeated Anunnaki left Earth. On their departure, they set off a cataclysmic chain of events that caused the Great Flood. This destroyed many living creatures on Earth, particularly all the Aryans and the stargates. The humans escaped the Flood and went with the Djinn.
Humans had been modified into effective killers by the Aryans, but this was then tempered by their time with the Djinn. The humans now became a creative species and in time gained more intelligence and compassion. When the Great Flood ended, humans returned. Some of the previous-type humans survived but were replaced.
Humans spread rapidly all over the Earth. They lived in large anarchist groups and the Earth knew peace for a time. There was a lot of trade and technologies were the developed to improve the lives of all humans. Unfortunately, the Earth was still part of the Anunnaki Confederation. It was only a matter of time before they returned.