The Earth was destroyed by the war between the West and the East which reduced the population of humans to somewhere around 30 million, down from 9.5 billion.
Prior to the war, an eccentric billionnaire constructed four interstellar colony ships that were meant to serve as humanity's last chance of survival. Approximately 20,000 people per ship, roughly 80,000 total.
After the destruction of the Earth, the spacefaring humans of Free Space, Luna and Mars banded together to render assistance to any survivors on Earth. When no survivors were found, a council was formed and the construction of the twelve interstellar colony ships was undertaken. Approximately 40,000 people per ship, roughly 480,000 total. Though many chose to remain in the Solar System, another group decided to construct a Cityship to take the rest of humanity to the stars.
The survivors of the destruction had retreated into subterranean refuges to wait out the wars. Perhaps 20 million people lived in dozens of underground cities by this point in time.
By this time, the Cityship had been completed carrying ten million of the rest of humanity on its way out of the Solar System.
Hundreds of thousands of years in the future
- SERAPH-DERIVED TECHNOLOGIES, technology of those that came before is very difficult to acquire, but the breakthroughs in propulsion and anti-gravity through reverse-engineered tech have led to greater expansion of humanity throughout the stars.
- GENECTIC THERAPY, fully biological humans as of the present day, are 198 cm tall on average, muscular, highly athletic and almost entirely maintain a 21st century meditteranean physical look.
- HUMAN LONGEVITY, fully biological humans can live up to 150 years old and it is not unheard to have encountered humans who have lived for over 500 years via artificial bodies.