It seems that Prophet's Rest is less a fortress and more an enclave or monastery. I suppose that would explain the name, now wouldn't it?
Yes as strange as it may sound, the natives have created a primitive religion centered around the ARK's obelisks. They pray three times a day, each time facing a different obelisk, and their robes bear a unique symbol - a three pointed star coloured red, green and blue. The blue obelisk appears to receive particular reverence due to is proximity.
As charmingly ignorant as their superstitions may be, it's far from the most savage religion I've encountered. Besides, Prophet's Rest is in need of a doctor, and I am in need of supplies.