Tsering Samdrup, above, patrolman at the Hoh Xil National Nature Reserve. [Photo provided to China Daily]

Back in 1997, the number of Tibetan antelopes were fewer as tens of thousands of them had been killed by poachers who would kill them and sell their wool to make shahtoosh (shawls) that were popular with the rich.

It was not until dusk on their second day at work that Tsering and his fellow patrolmen saw Tibetan antelopes from afar.

"They ran away swiftly on hearing the sound of the vehicle engine. They were very alert to the sound of vehicle engines because the hunters also drove," he says.

On seeing them the patrolmen asked each other: "Are they the legendary Tibetan antelopes? Nobody knew."

The core area of Hoh Xil, where Tibetan antelopes give birth, lies around the Zhuonai Lake and Taiyang Lake, respectively, about 140 kilometers and more than 300 km from the protection stations along the Qinghai-Tibet Railway line.

There, the weather changes rapidly as one goes deeper into the mountains.

The temperature can go as low as-46 C.

Even in summer, the temperature during the night is about -17 C.

An extremely difficult terrain with countless lakes and bogs, it is no man's land but a wild animal paradise.

Over the years, the men have patrolled the mountains of what is called the third pole, fought poachers and illegal gold miners.

The south of the mountains are the upper reaches of China's longest river, the Yangtze.

Since 2006, not a single shot has been heard in Hoh Xil. And the number of Tibetan antelopes has risen from 20,000 to more than 60,000.

Also, Tsering and his fellow patrollers now see more animals on the land: brown bears, lynx, Tibetan foxes, Tibetan gazelle, snow leopards, marmots, wild yaks, Tibetan wild donkeys, wolves and birds like kestrels.

Once, in a stony hollow, they came across a lonely rutting male wild yak, who ran madly at them, eyes shining and tongue lolling out like a dog.

It knocked over their vehicle as easily as a man kicks a stone over.