Unpacking references to “Arcadians”
Referring to themselves as “guardians”, [Arcadians] were often composed of societies which had the greatest bio-socio-psycho-emotional link to the lost Earth, and indeed a leading element of the guardian faction was made up of the final generations of survivors from the home planet. This set was determined to re-establish a new Earth on the nearest available Earth-like world, and might be seen as a ludicrous colonial throwback.
— “Posthumanity”, The Book of the War (2002), ed. Lawrence Miles
‘Where are you going?’ Steven asked.
‘The planet Refusis,’ replied the Commander. ‘The Earth is also dying and now we have left it for the last time. […] Only Refusis has the same conditions that we had on Earth. Atmosphere, water, the right temperate zones. […] We are the Guardians!’
— The Ark (1987), by Paul Erickson
Other groups were content to remake or even build worlds to be their new homes. Threatened by the rest of the [posthuman] hegemony, many of the Arcadian worlds eventually united to form a “benign union” (modelled on older world-systems which had displaced classical Greece and Rome as the acme of polite civilisation in the popular imagination). Faced with planetary atmospheres which bred goodwill and quiet contemplation by their very natures, the Arcadians’ enemies simply gave up. The Arcadian Union was isolationist and eventually the majority of its people simply vanished, either sublimating to a higher state of existence or dying of boredom.
— “Posthumanity” (continued), The Book of the War
Finally, on Traken, Nyssa’s home planet, the Master had captured the Source, the font of power for an entire galactic Union encompassing a million star systems. […] Chris recounted the sketchy details that he could remember: Serenity was the only surviving colony of the Union of Traken, a verdant garden world with advanced biotechnology, whose people lived in peace and relative isolation. They believed that at the time of the cosmic disaster that obliterated the entire rest of their galaxy, something called the Source had protected them, at the cost of its own existence. […] ‘We Adjudicators learn about Serenity as an example of a peaceful and just society.’
— Cold Fusion (1996), Lance Parkin
“Waiter! There’s even more Parkin lore in my book!” Or is there? (Emphasis all mine, of course.) From Big Finish’s Lost Stories adaptation of Johnny Byrne’s 1983 television pitch, which he’d shared with Sarah Groenewegen, a close friend of Kate Orman:
Sixth Doctor: Ahh, the planet Serenity of the Benign Union! […] This part of the galaxy, well, holds bad memories for me.
Peri: Do you want to talk about it?
Doctor: Well, you see that patch of darkness there at the edge of the screen? Now that used to be Mettula Orionsis, home of the Traken Union, one of the most harmonious places in the cosmos. […] That was centuries ago. At this point in history, a new union has risen in its place with, at its heart, the world of Serenity. The only planet of the Traken Union to survive.
— The Guardians of Prophecy (2012), Jonathan Morris