The former cradle of the Archaic Oikumene is a depopulated area without a central authority known as the Zuran Expanse. The Expanse is home to dangers like the inhuman Ssraad (in three colors), and ruined worlds that entice treasure-seekers like Tenebrae and the Library of Atoz-Theln. It’s also home to unusual cultures like the invertebrate Zhmun of Aygo and the self-improvement cult of Aurogov.
Old Earth is believed to be located somewhere in the Expanse, though the most likely candidate for the Sol System is quarantined by aggressive posthuman entities.