Evacuation of Kasath
The evacuation of Kasath, known as the Great Flight in Kasatha histories, was one of the largest exoduses in the history of Elyrion, taking place between 1147 and 1230 SSD. Following the Rathyn cataclysm of 1147, it became clear that the stellar conflagrations triggered by the collapse of the ley-lines would destroy all life on the worlds of the inner galactic core, while increasing cost and difficulty of faster-than-light travel over the following decade made an FtL evacuation of the entire population of the core infeasible. While a substantial number of people fled rimwards in faster than light ships, the majority of the core's population relocated to fleets of slower-than-light generation ships constructed by authorities under the Unified Evacuation Plan. Due to the constraints on trajectory imposed by the supernovae, most ships were forced to flee away from colonized space in the East, although a handful of vessels were able to make their way eastward; almost all artifacts of the pre-Silence inner core, as well as all surviving records of pre-contact Kasatha civilization, are found aboard (or in the colonies established from) the known ships launched during the Evacuation of Kasath.
Background
Although largely spared from the bloody conflict of the Ley Wars, the damage dealt to the ley-lines caused substantial disruptions to travel and trade in the inner core in the form of frequent and intense star-storms. As the major powers of the war fractured over the early 1100s, many outside polities hoped that large-scale hostilities would begin to wind down, with major space forces increasingly focused on battling domestic, rather than distant foes. Following the Rathyn cataclysm, however, this strategic calculus was upended. By late 1147 it became clear that the ley-line network would collapse completely within a decade, and most predictions indicated that this collapse would cause a chain of supernovae in the core, the radiation and plasma of which would destroy all life on the surrounding inhabited worlds.
Early Response
With an estimated population of five to seven hundred billion at the time of the cataclysm, it was immediately clear that faster-than-light transport would be unable to relocate the population of the inner core before ley-line collapse made FtL travel impossible, while ongoing turmoil in Aenaz made the prospect of large-scale resettlement in the region politically infesable. News of the impending apocalypse caused widespread panic, and a number of planets collapsed into near-total anarchy over the following years. Although regional authorities centered on Kasath began the development of long-term plans immediately, little central guidance was available in the first years following the crisis.
Almost as soon as the scope of the crisis became clear, almost the entirety of the region's passenger star fleet.