One of the hardest routes runs through five villages and includes about 12,000 people of the Tibetan, Hui, Qiang and Yi ethnic groups. It used to be part of the Long March (1934-36) by the Red Army and is full of revolutionary marks.
The high altitude is a hotbed for fickle weather while the complex plateau landforms make things all the more difficult for Lhalung Dorje.
He has had many close calls over the years as he has often encountered blizzards, mudslides, landslides and rockfalls.
The worst one happened in March 2018.
"It was spring but the temperature still lingered around zero and dropped to dozens of degrees below zero at midnight," he recalls.
"I was on my way home and suddenly a blizzard hit and the postal van slipped into a deep pit at the side of the road, causing the oil pipe to leak and freeze," he adds.
There was no cellphone signal, so he couldn't call for help.
"I had to rely on my experience to crawl under the van for repairs. I worked on repairing it for a while and then got back into the van to warm up. I must have done it a dozen times or so," he says, adding that the last time he crawled under the van, his clothes and pants were frozen to the road surface.
However, it didn't work, so he curled up in the driver's cabin, tired, hungry and cold, eventually falling asleep.
His colleague Sun Ping, who came to his rescue, still feels a chill when speaking about the situation.
"When we finally found him, it was already midnight. … He looked as if he had been frozen, covered all over with black oil and his hair stuck together," Sun recalls.
Those setbacks didn't hold Lhalung Dorje back and he continued on the road soon after.
"My job is ordinary. But within my abilities, there is nothing more meaningful than this," he says.
The three postal vehicles he previously wore out serve as proof of his commitment, which has also enabled him to witness the significant changes in Ruo'ergai's development.
"In the past, the roads on the grassland were uneven and full of potholes. It took four hours to travel 3 or 4 km. But now it's just a 30-minute round trip," he says.
