The Concordat of Peace was a treaty ceremony that took place in the capital city of Illyriaqüm on the planet, Shiva IV. The purpose of the Concordat was to unite together two warring factions on the planet, the Human members of the Calian Confederacy and the alien T'Syriél representatives that made up the Twelve Tribes of T'Syriél. Warlord, Aron Peacebringer forged a blood pact with the T'Syriél known as Kéral Longknife, thus ending decades of mutual strife.
The strength of the peace accords were bolstered in 3 ABY when Imperial forces sought to establish a foothold on Shiva IV. The Confederacy and the Twelve Tribes found a new enemy to fight against. With help from the Rebel Alliance, the two planetary factions succeeded in ousting the Imperials from Shiva IV.