The Passage of Nilor is an area in the Milky Way galaxy that used to be under Asgard control.
In 1999, the Asgard allowed the Goa'uld access to the passage in return for the System Lords' agreement to add Earth to the Protected Planets Treaty. (SG1: "Fair Game")
With the Asgards' destruction, it is unknown who now controls the passage. (SG1: "Unending")