The phrase "Great Cause" described the obligation of the Alanciari to defend against any invasion by the Lost Tribe of Sith, who held dominion over the adjacent land of Keshtah Minor. This concept of the Great Cause was initially brought to the continent of Alanciar by Adari Vaal, a Keshiri exile who had escaped Keshtah after a failed rebellion against the Sith in 4975 BBY. Vaal successfully alerted the Alanciari to the danger presented by the Sith, and consequently, the Alanciari transformed into a highly militarized and industrialized society over the subsequent two thousand years. The principles of the Great Cause were widely promoted among the Alanciari population through the widely read history book, the Keshtah Chronicles, as well as through Observance Day plays performed every decade.
From a young age, Alanciari children were indoctrinated into the Great Cause and expected to join the ranks of the Alanciari military. Even older veterans were expected to contribute to the war effort by working in glass factories. Force-sensitive Alanciari, such as Belmer Kattun and Quarra Thayn, were also enlisted as thoughtcriers, individuals with the ability to transmit telepathic messages via thought projection. Following the Sith conquest of Alanciar in 2975 BBY, the Great Cause was abandoned and systematically replaced by the Sith's "unification" policy for Alanciar and Keshtah. Alanciari were then taught to view the previous two millennia as a time of "collective delusion," given that the Tribe had already overcome the Destructors that they had been so afraid of.