Following the envoy from the Onyx Empire and his senior returning to the territory of the Onyx Empire, the surrounding empires soon realized that something had happened to their people. Not inside the Star Shattering Sect like they had expected, but instead on their way back from the Star Shattering Sect.
Given the information from the tracking formation inside the interspatial rings that their people had been using, it was obvious that they had been attacked shortly after they had left the Star Shattering Sect and had their things taken away.