The Great Cause was a term used to refer to the Alanciari duty to resist any invasion by the Lost Tribe of Sith, which ruled the neighboring continent of Keshtah Minor. The Great Cause had first been introduced to the continent of Alanciar by the Keshiri exile Adari Vaal who had fled Keshtah following a failed attempt to overthrow the Sith in 4975 BBY. She succeeded in warning the Alanciari about the threat posed by the Sith and the Alanciari developed into a militaristic and industrialized society over the next two thousand years. The Great Cause was disseminated to the Alanciari public through the popular history textbook known as the Keshtah Chronicles and Observance Day passion plays, which were held every ten years.

Alanciari children from young were raised to follow the Great Cause and were expected to enlist in the Alanciari military. Even elderly veterans were required to support the war effort by working in glass factories. Force-sensitive Alanciari like Belmer Kattun and Quarra Thayn were also recruited as thoughtcriers, individuals who were capable of sending telepathic messages through thought projection. Following the Sith conquest of Alanciar in 2975 BBY, the Great Cause was abandoned and phased out in favor of the Sith "unification" of Alanciar and Keshtah. Alanciari were taught to regard the past two millennia as a period of "collective madness" since the Tribe had already defeated the Destructors which they had feared.