Several worlds linked by religious and philosophical ties, mostly within the Cygexpa region. Founded by the Hippocratic Clade ethnicity in the 2500's on Chiri (Beta Canum Venaticorum III) and spread outwards towards Cygnus during the Age of Expansion.
The Confederacy was mainly involved in spiritual matters, and became a local hothouse of religious experimentation and exploration in the 4400's. Gradually it coalesced into a stable "mini Sophic League". It persisted with minor changes until 5944, when it was formally dissolved due to major emigration to other systems and demands for reform.
The Yoson Confederacy had a number of different colonies, many founded by ex-Eridanus League pilgrims as those worlds declined (resulting in the transfer of organized Etodism) but also mixed with other minority groups (and the exiles above; Etodists are fairly tolerant, although their missionary culture is strong).
The religious debates and turmoil included several re-interpretations of Etodist doctrine to justify violence (such as against the Tahmetian Crusaders who sometimes repressed Etodist minorities) but Etodists never really took to the concept of holy war. There was increased Etodist involvement in politics, however, and resultant concerns over potential corruption of the clergy.