The Purge

The Purge was a final act of judgement by the Coelestes.

Time
The Purge happened at the end of the Last War. With the Coelestes finally deciding to defeat the Te'an, they crushed Te'an fleets on all fronts, and stripped the Te'an civilization of all technology. For Millions of years afterwards, they monitored the advancement of Te'an society, keeping them from attaining weapons of planet-breaking capabilities, but with the rise of other advanced civilizations like the Ayam and Cetza, the Coelestes allowed the Te'an to continure their advancement.