Lord of Thunder.

Synopsis - No one had ever gone into the ‘Blue’ section of the planet Arzor and returned. It was the hunting ground of the terrible Norbie cannibals. Now there were rumours of an ominous gathering of the native tribes, which might mean the destruction of the planet, and Hosteen Storm’s brother was trapped in the ‘Blue’... This is Andre Norton’s second hair raising science fiction adventure about the young hero of The Beast Master (OL473459W).