"Unfortunately, there are many tourists now. And it is killing Jiuzhaigou. I see myself working against time because, as the beautiful places in China become popular, they may eventually lose the magic with so many tourists going there."

However, it is the human geography that most fascinates the photographer.

Yamashita has completed many big projects as one of the few photojournalists who has worked for National Geographic for more than three decades. He has mostly worked in Asia, largely because he's linked to the continent as a third-generation Japanese-American.

He has fused his photography and travel passions by retracing the routes of celebrated explorers, including Marco Polo, Japanese poet Matsuo Basho and Ming Dynasty (1368-1644) explorer Zheng He (1371-1433).

But, unlike Yamashita, they didn't have cameras.

"Every photographer loves being in a situation where you are there first (and) anybody else needs to follow your lead," Yamashita says. The images he has captured take viewers on many journeys.

They can experience contemporary celebrations for King Gesar, a mythical Tibet an figure who defeated evil tribes to unite the ethnicity. They can slip into the kitchen of a Tibetan temple where monks perform morning tea services. They can scale the 4,000-meter-high mountains to see how Tibetans dig caterpillar fungus - a parasitic fungus that sprouts from the corpses of ghost moth larva - and can sell for $10 for a 1-centimeter-diameter piece.

Yamashita explains Tibetan monks aren't friendly toward photographers. He was the only one at the King Gesar festival, largely because it's difficult to access the location.