During the Web Era, the Hegemony terraformed most of the planet, primarily the areas around its equator. The planet had a breathable atmosphere then, and was populated with Old Earth wildlife. The All Thing, however, prevented its full terraforming - leaving the areas in the north reaches of the planet intact for the survival of the native alien lifeforms known as the Wraiths.
After the Fall, Sol Draconi Septem quickly reverted to its original state of hyper-glaciation, with the atmosphere freezing almost totally solid and forming a thick blanket of ice over the entire globe. When that happened, the wraiths reestablished their domain over the entire planet, and engaging in a symbiotic hunter-prey relationship with the Chitchatuk, who navigated the frozen land using the tunnels bore by the creature's cubs.
SPOILER ALERT! The section(s) below are MAJOR SPOILERS.
Wraiths. Contribute to Hyperion Cantos Wiki by expanding this section.