Terramayara was a human colony in the Orion Quadrant near the center of the galaxy, settled in prehistoric times (At least 2000 Years before Solar Century Zero) by a 51st Century colony ship (Ra) that encountered a time warp (that was caused by Trajan Lear and Matthew Driver messing around with the Chronos Starlock).
The colonists started a human civilization based on the principles of Starcross, a religion originating in the 43rd Solar Century, because of the efforts of Starcross Missionaries who were among Ra's passengers. The civilization thrived and prospered for many centuries before being wiped out by a species of giant mutant space broccoli.
The planet was rediscovered by the explored Brian Kingman in the 43rd Earth Century, who used its sacred text to found the Starcross religion.