Outer Vigil
From Halo: Daybreak
The Outer Vigil is an alliance of post-Covenant polities who are also signatories of the Concord of Reconciliation, and are generally located in the outermost regions of the Holy Ecumene. They routinely cooperate closely in the matters of military and security with each other, although in some cases the Concord's authority is more symbolic than anything. All members are allied with the United Earth Government, although this does not make them friendly by any stretch.
The Concord entities that inhabit the Siakar Expanse and nearby domains are part of the Outer Vigil.