On a clear morning in late September, a group of border police officers departed from the Dulongjiang station in Yunnan province to complete a five-day patrol of a border marker at 4,100 meters above sea level. The route, spanning nearly 80 kilometers through dense forest and unstable slopes, is emblematic of the daily challenges in this remote township in southwestern China.

The group set off with food for several days, spare clothing, emergency gear and a satellite phone. There was also something else, written the night before and left behind: letters to their families.

"We all knew what kind of road we were about to walk," said Zhang Qilei, head of the Dulongjiang township border police station in Gongshan county. "Out there, if something happens, help can take hours just to reach the foot of the mountain. After that, it would depend on whether they could find us in time in the forest."

For almost a week, the team trekked, hauling 20 kilograms of supplies each, crossing rivers by hand, probing mud with bamboo poles, and climbing slopes so steep they relied on ropes to pull one another up. At night, they slept in damp air. There was no signal, only a brief daily check-in by satellite phone to report their location.

When they reached the marker, the tension finally broke.

"It's hard to explain that feeling," Zhang said. "Pride. Relief. You've been holding it in the whole way."

Hours later, as they made their way back, the weather turned. Rain came down hard enough to collapse their tents.

They were fortunate, Zhang said. "If it had rained earlier, we might not have made it."

For decades, journeys like this have defined life in Dulongjiang, a remote township tucked between steep mountains and the Dulong River valley near the border with Myanmar. The region, home to just over 4,000 people — most of them from the Derung ethnic group — was once among the most isolated places in China.