From Roy Chapman Andrews' excellent book 'Across Mongolian Plains' published in 1921.
Half an hour later we sat down for a look around. I studied every ridge and gully with my glasses without seeing a sign of life. The four sheep had disappeared as completely as though one of the yawning ravines had swallowed them up; the great valley bathed in golden sunlight was deserted and as silent as the tomb.
I was just tearing the wrapper from a piece of chocolate when the hunter touched me on the arm and said quietly, “Pan-yang li la” (A sheep has come). He pointed far down a ridge running out at a right angle to the one on which we were sitting, but I could see nothing. Then I scanned every square inch of rock, but still saw no sign of life.
The hunter laughingly whispered, "I can see better than you can even with your foreign eyes. He is standing in that trail — he may come right up to us."
I tried again, following the thin, white line as it wound from us along the side of the knifelike ridge. Just where it vanished into space I saw the sheep, a splendid ram, standing like a statue of gray-brown granite and gazing squarely at us. He was fully half a mile away, but the hunter had seen him the instant he appeared. Without my glasses the animal was merely a blur to me, but the marvelous eyes of the Mongol could detect its every movement.