Backstory
Through the course of Ascending, Gardner adds depth, detail, and perspective to the conceptual background he has established for the "League of Peoples" series. In particular, he explains how human beings and other species in the galaxy are contacted by, and become a part of, the larger galactic community.
Sometime in the middle of the 21st century, humanity encounters a mysterious group of beings who call themselves merely "citizens of the League of Peoples;" others call them the Shaddill. The Shaddill explain the grand design of the League: sentient species who renounce the use of fatal violence against other sentients can join the League and share in its wealth of advanced technologies, including terraformed planets, genetic engineering, "star drives" for effective interstellar travel, highly advanced medicine, and other advantages. The Shaddill offer to transport humans to a terraformed New Earth where none of the old problems of the "old Earth" will exist. Their offer stands open for twenty years. At first only the most disadvantaged and unhappy members of human society take the Shaddill up on their offer; but when they return to visit Earth in a year or two with tales of their wonderful new lives, the exodus increases— which causes more and more problems for those who remain behind. By the time the Shaddill's 20-year offer expires, the only people left on Old Earth are those too stubborn or violent to make the leap to a new society, and who must subsist in the collapsed remains of the old.
By the end of the novel, however, it becomes clear that the Shaddill have been offering a Faustian bargain: the beneficiaries of their largesse employ technologies they do not really understand, the full consequences of which they cannot perceive. The true motives of the Shaddill turn out to be far less benign and magnanimous than anyone had suspected.
Read more about this topic: Ascending