The Rim Territories was founded by the union of four ex–Rim Worlds Republic planets - the independent worlds of The Rack and Pain and the former Lyran planets of Engadine and Main Street - and either then or later included six more colonies settled by refugees from the Blakist Jihad.  
Government and Society
Officially the Rim Territories was founded as a mutual defense and trade pact. In reality it is first and foremost a collective of pirate groups who each control a world and organize it along the lines of a criminal fiefdom. Despite the nature of its government, however, the Rim Territories has survived for six decades and proven to offer more stable government than the average independent Periphery world.
- Field Manual: 3085. p.231 (p.249 pdf)
- Field Manual: 3085, p. vi, "Inner Sphere October 3085" map - only Pain, The Rack, Engadine and Main Street are shown as settled worlds at this point
- Era Digest: Dark Age, p. 12, "Map of the Inner Sphere 3130" - the other six member worlds are extant by now
- Dark Age: Touring the Stars (3130), Vol. XLVIII: Denizens of the Periphery
- Shattered Fortress, p. 54, "Piracy Rampant in Rim Territories"
- Shattered Fortress, p. 100, "Timeline of Events: 3146-3150"
- First Succession War, p. 101, "Rim Territories"