From the rules text:
It’s been ten million years since the humans left this Earth. They left it polluted, exhausted, spent. Irradiated ruins, acidic oceans, scarred earth and mountains of waste. While the humans floated through the ether, held in stasis in their hermetic capsules, the Earth has endured. She has lived on, transformed, evolved. Those same malignant forces the humans unleashed have shaped the Earth’s development. And in ten million years we have evolved – the Sapients, the new masters of this old planet. We are as diverse as we are intelligent. We are resourceful and adaptive. This Earth is not one the humans would recognize, but it is our home. And now, we must defend it. After ten million years, the humans have returned. They have come to make a new home on a new Earth, to settle and expand and consume and conquer. Can the ragtag, disunited Sapient coalition save the earth from humanity?