But for decades after the Korean War in the early ’50s, which ended with Korea divided by a sealed border, South Koreans were barred from visiting by North Korea and China, the North’s Cold War ally. Under their 1962 border treaty, North Korea and China each owns roughly half of the mountain and Cheonji.

The door opened only in 1992, when China and South Korea forged diplomatic ties.

South Koreans began rushing to Baekdusan, climbing the Chinese slopes of the mountain. Barring the reunification of the two Koreas or a sudden decision by the North to open a land route across the Korean Peninsula — both prospects distant, given high tensions on the peninsula — the route through China is the only way for them to visit their “holy mountain.”

That devotion has not been without problems.

Once on the mountaintop, many South Koreans are moved to display their national flag, chanting hurrahs with arms raised, and singing their national anthem — raising the hackles of North Korean border guards nearby. In 2008, a cast of celebrities in a popular South Korean reality TV show traveled to Baekdusan with bottles of water collected from remote corners of South Korea and poured them into Cheonji in what they called a symbolic gesture of making the divided Korea whole again.

Today, local guides, mostly ethnic Korean-Chinese, recite a strict Chinese government ban on such activities.

“Please no national flags at the top,” one of them said. “This is not your Mount Everest.”

The stunts have largely come to an end in recent years, with many Chinese national park officials around at the scene to enforce the ban.

“There is something about Baekdusan that makes all Koreans patriotic,” said Lee Byong-chul, senior fellow at the Institute for Peace and Cooperation in Seoul, who visited the mountain last year with a group of former South Korean government officials and scholars. “There, Koreans feel they have come to their roots.”