The Mandalorian Avengers was a sect of Mandalorians headed by Clan Ordo and led by Atin Ordo. They were founded at Taalhir, Mandalore, at the Verd'Ka'rta homestead. The first three Clans to found it were Clan Ordo, Clan Verd'Ka'rta, and Clan Xarga. Later, Clan Baatir would join them, followed by many others. The Mandalorian Avengers were formed as a resistance to the oppressive reign of the Mandalorian Commandos who were led by a Mand'alor who stole power. The conflict between the two would come to be known as the Second Mandalorian Crusade, when involvement of the Sith was discovered. A'tin and his clan learned that the Mand'alor was dealing with the Sith, and used that information to unite most of the Mandalorian people not already under the Commando and Sith control.
Soon after the Mandalorians were united, the majority of the Commando Military was defeated, but the remnants were enslaved to serve the Sith as foot soldiers to complement the acolytes who hunted the Avengers. A wide spread war broke out between the Mandalorians and the Sith, covering most of the Outer Rim, and Mandalorian planets.