Xi'an terraforming practice is unique among known civilizations. Rather than only creating a biome to sustain life, Xi'an terraform planets to fit functions seen as necessary to the well-being of Xi'an society. Some functions include manufacturing, nature preservation, and religious centers.
The Xi'an discovered terraforming roughly 6000 SEY before the beginning of the First Imperial Age (about 25400 BCE), when a series of volcanic eruptions forced the then-divided Houses to pool their resources to push back against the rapid cooling of their home planet. Early geohacking machines, the precursor to platform-based terraformers, stopped the catastrophic global cooling cascade before it could end life on the planet. Today, the Xi'an use the Th.us'ūng system as a testbed for advanced terraforming technology.