From the introduction: Sangoro’s Bulwark was among the most fortified Starfinder Society strongholds outside the Pact Worlds. Serving as the headquarters of the Exo-Guardians and bearing the name of its vesk discoverer, the fortress was located on a hidden planet in the Vast surrounded by interplanar anomalies. It was impossible to locate, much less attack—or so the Exo-Guardians assumed.