Zhao Xuyang, the 49-year-old director of the Xianyang Archaeology Institute and head of the team of Shaanxi province's Xianyang city for the fourth national census of cultural relics, had, quite literally, lost track.

It occurred as he was with several young team members rechecking the Qinwangdian Site, ruins of buildings in the remote mountains of Chunhua county, Xianyang, dating back to the 4th to 5th century for the fourth national census.

Although they had GPS data, photos and descriptions of the site left by the third census conducted from 2007 to 2011, they struggled to find paths leading to the mountains, since the people who had lived there moved out in recent years, in response to the proposal of returning farmland to forests for ecological, environmental protection. With fewer people traversing these routes, the mountain pathways gradually faded away, causing the sites to become obscure and Zhao and his colleagues to lose their way.

Fortunately, they met a local man surnamed Yang in his 70s who had previously resided in the mountains but had left years before, only returning occasionally to gather herbs. After a two-hour hike through the hilly terrain, the man guided them to the site.

"If not for Yang, we would not have discovered the location. Looking around, the environment has changed tremendously compared to photos taken before," Zhao says. "At that time, the site was covered with wild grass but is now part of the forest. By checking the stone architectural components left, we identified the site and completed the census work."

Zhao thanks Yang for his help. "Growing up in the mountains, he has traversed every path, possessing an intimate knowledge of the terrain, which enabled him to lead us to the site," Zhao says, adding that such sites, nestled deep in the mountains, may fall into oblivion without helpers like Yang.

These invaluable heritage sites are swept off dust that allows them to reveal their ancient yet charming visages. In this way, the census is a rare opportunity to record cultural relics in the wide territory and involves passing the experience down from generation to generation.

Zhao says he told his young colleagues to remember the experience.

"It's a meaningful trip. During the next fifth census, my colleagues may not find other people who still know the paths and I will probably retire by then. But they still know how to get to its location and can pass on the information to future generations, so it doesn't disappear," Zhao explains.