The Concordat of Peace represents a treaty signing event. This event occurred in the capital of Illyriaqüm, a city located on the world known as Shiva IV. The Concordat's goal was to bring together two factions previously at war on the planet: the Human members who belonged to the Calian Confederacy, and the alien T'Syriél representatives forming the Twelve Tribes of T'Syriél. Through a blood pact between the warlord Aron Peacebringer and the T'Syriél named Kéral Longknife, decades of conflict came to a close.
The peace established by the Concordat was reinforced in 3 ABY as Imperial forces attempted to gain control of Shiva IV. Facing this new threat, the Confederacy and the Twelve Tribes united against a common foe. Aided by the Rebel Alliance, the two groups on Shiva IV successfully expelled the Imperials from their world.