The Anu came from a star system very far away from Earth. They did not evolve with the fluctuating energies of magic as a constant presence throughout their development. Because of this, and because their species functions predominantly on a mental, intellectual level, they were not aware of the meta-energies in this part of the galaxy.
And yet, these energies became the downfall of their mission on Earth.
When the first golden age came about, the Anu in orbit around Earth were affected them in a way they did not see coming. At first, they responded like they were on drugs. Over the space of many millennia, these once beautiful, peaceful people became increasingly savage, paranoid, greedy and started to squabble amongst each other.