Adventurer, researcher and Great Wall expert Dong Yaohui is penning the ancient bulwark's most comprehensive chronicle. Han Bingbin reports.

Dong Yaohui's mission is nearly as great as the wall he is chronicling - and is perhaps even greater than his successful quest to become the first person to trek the entire Great Wall decades ago. The vice-chairman of the China Great Wall Association is undertaking this mammoth task in a tiny office at the foot of the Badaling Great Wall.

Here, he says, he can shut out all distractions to focus on writing China Great Wall Chronicles, the most comprehensive academic record of the ancient bulwark to date.

Dong Yaohui, vice-chairman of the China Great Wall Association, is undertaking the mammoth task of writing the China Great Wall Chronicles, the most comprehensive academic record of the ancient bulwark to date. Kuang Linhua / China Daily

All the 55-year-old has done virtually every day since 2007 is write and trudge up the mountain twice a day to get exercise and maintain contact with the wall. The 25-million-word volume is slated for publication in 2015. It examines 17 dimensions of the ancient fortification, including its geography, architecture and military functionality.

Every chapter examines a different dimension of the wall. Dong compiles experts' research into a single narrative arc.

He is often invited to lead tours for visiting senior foreign officials. But he finds that, despite his expertise, he is often unable to answer some of the most elementary questions, such as those about the wall's total length.

In such cases, he cites historical records but often finds these don't match reality, he says. For instance, one record says the Great Wall in Beijing is about 300 km, but an air survey in the 1980s determined it's 629 km.

But the problems with understanding the Great Wall go beyond numbers. Dong says he started his literary project because the vastness of the wall as a topic has meant no systematic method of studying it has been developed.

"People were very supportive when I proposed the concept," Dong says.

"I haven't otherwise seen the experts on the same page in 30 years. Three decades ago, they all thought I was crazy."

Such an assessment of his mindset might hail back to his history. In 1982, the then 25-year-old worked as an electrician, who climbed and maintained the transmission towers on the Great Wall's easternmost pass in Hebei province's Shanhaiguan. One day, while staring at the wall snaking across the mountaintops, he vowed to become the first person to trek the entire wall.

And he did.

After two years of poring over historical records, he quit his job and set out with two friends on May 4, 1984, leaving behind his wife and 1-year-old daughter.

The trio spent 508 days trekking through 110 cities to reach the westernmost terminus at Gansu province's Jiayuguan pass.

It's an adventure many have since replicated.