From Destinypedia, the Destiny wiki
Xûr's Dominion is a location within Eternity, in Unknown Space, in Destiny 2, released with the 30th Anniversary Pack. It is a small, gold-plated area that serves as an antechamber for Xûr's Treasure Hoard. If one goes the opposite way, they will reach a teleporter that brings them to the Valley. The Dares of Eternity begin in this location.