Aetorian League
Centered around Aetor, the League (at its maximum extent) included Tethys, Zinnberg, Bosip, and much of the surrounding areas.
Aetor was colonized in 2098 CE
After the fall of the First Empire Aetor became a minor player in the region, but always remembered that it was one of the founding worlds of the Empire. In 4518 Aetor, with a few surrounding worlds, proclaimed the Aetorian League. In 4601 Aetor-Tethys-Zinnberg-Bosip signed the Aetorian Pact for mutual co-operation. The individual states and planets kept considerable autonomy and continued to exist as distinct entities. This is the traditional date of founding for the Aetorian League.
The League remained a minor player on the Galactic stage until 6697, when Lathyros declared war. Tethys, Zinnberg, and Bosip made individual settlements with Lathyros, withdrawing form the League. Although the Aetor-Lathyros War dragged on until 6712, when a treaty ceded most of the Aetor's's territory to Lathyros, historians date the end of the League at the start of the War, 6697.