Atlanteans

The Atlanteans are a hyper-advanced Tier V civilization that exists beyond any known space and are considered the oldest existing civilization and race in the Milky Way. They held form the Confederacy of Worlds around 200,000 years ago. Even though they are known to exist their known forms are mysterious as they maintain little relationships between carbon-based lifeforms. However it is believed that they have helped guide various species in their development including humans at some period in time. However they are believed to have existed on Earth at some period giving rise to the Greek Gods at one point. They also have been known to give "hitch-hikes" to species off their dying-home world and seeded onto a new world without their knowledge.

History
The Atlaneans known history indicates that they arose around the time of the Progenitors but were at some period in their history inhibited from developing beyond a Tier I Civilization and revolted and formed an alliance between an unknown species. Around 1.2 billion years ago they became embroiled in an eons long conflict between the Progenitors and became known as the boogey-men of the Galaxy. Their conflict would end around 400,000 BCE when they ended the war with the Progenitors during a battle which destroyed their home world. Following this their civilization too vanished but representatives from them continued to appear on other worlds guiding various species to presumably proven the same mistake they made. At one point in history they were recorded by the Ta've to have held a presence on Earth during the early dawn of human civilization being believed to be the Egyptian and Greek Gods. It is theorized that they determine a species to be worthy to develop beyond this point to prevent a inter-galactic war.