Rao Zijun, the director of the documentary Hidden Land in Northern Tibet.[Photo provided to China Daily]

En route toward their destination, the highest peak in Purog Kangri, the majority of the crew suffered from altitude sickness. Chen Guiwen, the 51-year-old photographer who has wished to explore deep into the unmanned area for years, failed to realize his dream as he was diagnosed with acute lung edema on the first day.

Besides, wild animals had also become a potential threat. A giant wild yak attacked one of the vehicles and tried to overturn it. Luckily, the skillful driver avoided the hostile beast.

With nearly a third of the crew quitting due to health problems midway to their destination, the remainder finally arrived at their destination - the heartlands of Purog Kangri formed by glaciers millions of years ago.

"Time stops here. The secrets of the history of the Earth were all laid out in front of me," says Rao Zijun, who put on her late father's red down jacket to climb the peak.

But she had to stop at 6,000 meters as she was suffering from serious breathing problems in the freezing, windy conditions, where temperatures drop to as low as minus 40 C.

Rao knew the summit of Purog Kangri was more than 6,800 meters above sea level after researching the area extensively before setting out on the long-distance journey. Yet the rest of the crew were forced to stop at 6,200 meters due to the harsh conditions.

But the young filmmaker still feels grateful about being able to direct her maiden feature in an area that only a few people have ever set foot in.

"I'm the first and only student in my university class who has shot a feature-length film. I feel very lucky and hope to shoot more works about Qiangtang. It's so vast and still has a lot of areas that remain to be explored," adds Rao.