Terraforming is the process of rendering an environment habitable for particular inhabitants through the use of industrial technology applied on a planetary scale. Humans have been terraforming worlds since the early 22nd century, allowing for a more rapid expansion into the galaxy than would otherwise be possible. Xi'an have been terraforming since roughly 25400 BCE. Terraforming is an extremely difficult process. When done incorrectly or with substandard materials and processes, it can lead to major disasters. It additionally has a devastating effect on existing flora and fauna on the planet and can lead to mass extinction events.