"Many ages ago, our peoples lived on a wonderful planet. The living beings on it were beautiful, and plenty. The millions of lifeforms had found a perfect equilibrium, living in symbiosis with each other. The climate was diverse, and beneficial to life - thus, all life was flourishing. It was an Eden in the middle of the Milky Way.
At a certain point in time, our peoples started evolving in their technology with increasing speed. Food production went higher, the population exploded.
Our people were so occupied with the new-found technology and progress, that they lost their eyes for the beauty of life. They lost connection with mother earth - they called it 'nature', as if it was something different than themselves. They became distracted, with what they called 'success', and 'growth'. But they didn't mean growth like we understand it, as a realisation of potential, as a striving for goodness to the benefit of all. For them, it was a measure of how much single individuals were able to exploit the available resources of the planet they all lived on, the planet that belonged to all of humanity, to all of the animal kingdom and to all of the plants. Also, it was a measure of how much they were able to exploit one another: Other human beings who had in their understanding less right to survive, less right to receive food and shelter. Those beings were forced to trade their time and labor for paper, which possessed value to them, which they were able to trade for food and shelter.
To understand their concept of 'success', and 'growth' on the cost of their very life source, and on the cost of their fellow living beings, you need to know that they didnt feel yet that we are all one. That the harm of another human, animal, plant or planet, would eventually fall back to themselves.
Only few of them were not completely blinded by their concept of 'growth', 'progress' and 'success'. They saw the beauty of nature, the appreciation for the miraculous planet they lived on, the legacy of their ancestors. They saw the social injustice, the ecological devastation, the cruelty, the doom towards which they were heading. But they had no power to change it.
So the inevitable happened, and earth became uninhabitable. Most of it's human inhabitants died - with them countless species of animals, and plants. The planet was polluted beyond repair, and stripped of all it's resources.
Thus our peoples had to leave. The galactic federation didn't have much mercy: our peoples inhabited one of the most beautiful and diverse planets in the galaxy, and they destroyed it. They were fortunate enough to be allowed to survive, though on a planet with very harsh living conditions and no other live on it whatsoever.
This is how we came here. The beauty of planet earth lives on in our collective memory, and the mourning about it's loss is still causing pain in the souls of our peoples. But we have to be faithful, and keep the hope. Maybe one day, in the far, far future, we will be given another chance."