"Another World. Another Time. In the Age of Wonder. A thousand years ago, this land was green and good...until the Crystal cracked. A single piece was lost, a shard of the Crystal. Then strife began and two new races appeared: the cruel Skeksis and the gentle Mystics..."
Specifically, the planet featured in the film is “fractured” into two opposing, extreme camps, Mystics and Skeksis. Each camp relies heavily on thousand-year old rituals, but finds "no satisfaction" in the rote repetition of them. And that’s because each side is incomplete, flawed, and even bored. The Skeksis are rather overtly flawed of course, giant vulture-like creatures interested only in avarice and their own unhealthy appetites. But the slow and deliberate Mystics are flawed as well -- too slow and contemplative to really live life to the fullest -- and only the “Great Conjunction” can heal the planet and bring the two races together.
Virtually alone among movie fantasies, The Dark Crystal concerns healing and completeness, and the idea that to be "whole," we must join with and "absorb" the “darker” part of ourselves...even if we don’t want to. For as bad as the Skeksis surely are, their percentage of the equation cannot be absent in the totality of identity. What we see embodied in the film, then, is a relatively realistic and integrated view about mankind. Like these alien creatures, we are not without a dark side, and the dark side even has a place in our gestalt, but we must decide how to harness it appropriately.
“What was sundered and undone shall be whole - the two made one.”
By that, I mean the creatures weren't generated by a few deft keystrokes on a computer and then added to a live-action sequence later on. Instead, these colorful, breathing, wondrous things -- the denizens of this unique world --- had to be designed, built, wrangled and performed. They had to be a real physical presence on the sets. They had to be managed for the camera. The filmmakers had to contend with putting these creatures out on location in some instances, in the rain and elements.