To his utter amazement, however, the fierce-looking warriors, open mouthed and apparently terror-stricken, slunk backward, huddling together, all the time staring at him with bulging eyes.

His first thought was that they were surprised to find him so bold, but the next act on their part caused him to gasp with wonder.
With one accord the entire band cast weapons aside and fell face downward, beating their heads against the rock, just as he had seen Arabians and Nubians perform in saluting some mighty potentate.

The brown backs remained in that position for a full minute before he could call his trembling companion to his side.
"What does it mean ?" whispered she at last.

"Are they dead ?" "They are really there, then?
By George, I thought I was dreaming.
Tennys, they are actually doing us homage." "Then they are harmless," she cried joyously.
"I believe I could go down and cut off their ears without hearing a protest." "But you won't, will you ?" "It would be barbarous, totally uncalled for, I'm sure.

I can't understand their warlike appearance, though.