Complex sentence: When they awake from the shock of the pressure change they are prisoners of humans dressed in primitive robes and bearing tridents, but they mean little harm and herd the travellers into another room where a large spread has been prepared.
Split into simpler sentences: When they awake from the shock of the pressure change they find they are prisoners of humans dressed in primitive robes and bearing tridents. Yet these captors seem to mean little harm and they herd the travellers into another room where a large spread has been prepared.