From the introduction: At the dawn of the 23rd century technology had replaced the concept of Humanity with that of Sentient. The advances in nanotechnology, genetics and cybernetics populated the world with a variety of intelligent beings (AIs, robots, uplifted animals, synthetic humanoids, cyborgs) whose rights had to be recognized and regulated in order to avoid social unrest. At the same time the consumption of material resources had finally forced the Earth Unity of Sentients (also known as EUS, a "soft" world government that had replaced the UN) to a concrete effort in the colonization of the Solar System. ... Ten centuries have passed since the collapse of the EUS.