According to Yan, they followed previous satellite positioning data on the site to look for it in July last year but initially couldn't find traces. Unwilling to give up, they began to scour the surrounding areas.

After two days they found remains of a building with a format very similar to other existing karun in Horgos. Its relative location to reference points, like a cliff, a snowy mountain and trees, was similar to its old photos.

After consulting experts, they were sure this is the karun they were seeking.

"A main reason we could find it this time is that we have more advanced equipment than before, which could guide us anywhere we wanted to go to in a more accurate way. This discovery is a big reward for us in this census," says Yan.

Many of Horgos' sites are in remote mountainous areas where few people can access. Team members have to improvise. They often saddle up and ride horses or hike in the mountains. In border areas they are often accompanied by frontier guards.

Yu Baoqin, a 52-year-old team member, says it was not easy to complete their tasks. When their field work started in July last year, they visited mountains with no trees to provide any shade. Locusts were rampant, posing a big challenge.

"When we visited sites on the Hantian Mountain last year, every time we opened a bowl of instant noodles, locusts jumped into our faces and into the bowl. It seemed to be a competition between people and the locusts to see who could gain the first bite," says Yu.

Riding horses sometimes can become a challenging experience for them as well. Zhang recalls last July, they went to check some unknown tombs local people reported to them on a mountain. On their way back, they were riding horses on narrow mountain paths, but one of the horses was suddenly startled and began to buck. A team member on it fell off. Luckily, he was not badly injured.

Worried that it would startle other horses, team members all jumped down from their horses and began to hike in the mountains by themselves. The horses, instead, were led by herders to return. Finally, team members spent more than five hours walking back to the city.

"Although we met a lot of problems, we viewed them as nothing but experiences in life and haven't felt frightened to face them. We are so honored to be members of the census and all we have thought is to accomplish the tasks in a satisfying way," says Yan.