NANNING/GUANGZHOU -- Hidden for years in a flowerpot behind Zhan Pu's childhood home in the southern Chinese city of Shantou, a faded letter told of gratitude for a secret donation from Thailand to China during World War II (WWII).

Zhan, 95 years old, recalled that it was a reply letter signed by Zhou Enlai, who later became Chinese premier. "It responded to my father's friends in Thailand, who had remitted funds to support the Communist Party of China's resistance against Japanese aggression."

The money had traveled through the qiaopi network, a unique system that blended letters and remittances sent by overseas Chinese, mostly in Southeast Asia, via civil agencies, financial institutions, and the postal service.

What struck Zhan most was that even after the Pacific War erupted in 1941, bringing much of Southeast Asia under occupation, the qiaopi network found ways to survive, sustained by hidden routes and local courage.

One critical link was Dongxing, a small border city in Guangxi Zhuang autonomous region, separated from Vietnam by just a river. As one of the few gateways along China's southeastern coast not sealed off by Japanese forces at the time, it anchored a clandestine 3,000-km remittance route connecting China with Southeast Asia.

"The Dongxing route not only moved large volumes of qiaopi, but also funneled donations and supplies from overseas Chinese to support the Chinese People's War of Resistance Against Japanese Aggression," said Chen Xiongzhang, a professor at Nanning University.

Today, along a narrow street in Dongxing, a weathered small building still stands, its faded walls holding echoes of history. Once a bustling transfer station, it has been transformed into a modest museum keeping these stories alive.

"These yellowed qiaopi documents are like historical footnotes, bearing witness to the profound friendship between the peoples of China and Southeast Asia in their fight against Japanese aggression," said Mo Xiaoning, a tourist from Nanning, capital of Guangxi. "They remind me that today's peace is not something easily achieved."

SHARED HISTORY

Beneath a searing sun, trucks loaded with fruit, machinery and electronics rumble through Youyiguan Port, whose name means "friendship" in Chinese, one of China's busiest land crossings into Vietnam.

More than 80 years ago, the same gateway carried very different traffic: military and civilian supplies channeled from Vietnam's Hai Phong port through Dong Dang to China's embattled front lines and rear areas.

Hundreds of overseas Chinese drivers and mechanics from Southeast Asia, known as Nanyang Volunteers, risked their lives to keep this critical supply route operational between 1939 and 1940, said Li Jianping, a senior researcher at the Guangxi Academy of Social Sciences.

"The road, along with the courage and cooperation of these volunteers, helped secure victory in the Chinese People's War of Resistance Against Japanese Aggression and the World Anti-Fascist War," Li said.

Their story resonates to this day. In a museum in Penang, Malaysia, a gentle wash of incandescent light falls across rows of faded black-and-white photographs, preserving the legacy of the Nanyang Volunteers.

For Li Chenye, a Chinese student studying in Malaysia, their sacrifice has left a lasting impression.

"Every time I hear about the Nanyang Volunteers, I feel such deep respect," he said. "Their contribution was vital, for the nation, and for history."

That shared history of WWII continues to inspire younger generations across Asia.

This year marks the 80th anniversary of the victory of WWII. In May, a group of young Vietnamese visited the site of the office for the League for Independence of Vietnam in Jingxi, Guangxi, a base for Ho Chi Minh and other Vietnamese communists in the early 1940s.

"For a long time, I only knew that late President Ho Chi Minh spent some time in China fighting invaders during WWII," said Hoang Thi Bich Diep, who joined the visit. "Seeing so many historic sites made me truly feel how Chinese and Vietnamese youth share a common history of solidarity in hard times."

UNDYING BOND

Experts believe these shared memories deserve even greater protection and promotion, both for education and for future cooperation.

"Sites like former qiaopi agencies, the Guangxi-Vietnam Road, and landmarks tied to Ho Chi Minh can all be preserved and promoted to help strengthen bonds between China and Southeast Asia," said Zhao Weihua, director of the Center for China's Relations with Neighboring Countries at Fudan University.

"These efforts can deepen people-to-people exchanges and help foster a stronger sense of the China-ASEAN community with a shared future," Zhao said.

Pham Thai Hung, a Vietnamese businessman in the tourism industry, has seen growing interest among Chinese travelers exploring Vietnam, as well as more Vietnamese visiting China.

"Our countries are geographically close and culturally connected," he said. "I'm confident about the prospects for tourism cooperation, and we will design more tourism routes to match visitors' interests."

Beyond tourism, economic ties between China and Southeast Asia continue to expand.

The Association of Southeast Asian Nations (ASEAN) remained China's largest trading partner in the January-May period. During this period, trade between China and ASEAN totaled 3.02 trillion yuan (about $422 billion), a year-on-year increase of 9.1 percent.

Amid geopolitical tensions and global uncertainty, the importance of preserving these shared memories has only grown, said Chen Guobao, a researcher at Guangxi Normal University.

"By revisiting historic sites, younger generations can better understand how hard-won the concept of win-win cooperation is and why cooperation remains the only viable path to shared development," Chen said.

That spirit of preservation has taken root in Zhan Pu's hometown as well. A dedicated qiaopi museum opened there in 2004, now housing some 90,000 documents, mostly from Southeast Asia, and attracting around 140,000 visitors each year.

The museum has adopted digital tools to conserve fragile documents and is upgrading with intelligent guides, VR experiences, and multimedia displays to enrich the visitor experience.

Zhan's family treasure — that precious letter of thanks — eventually made its way to a museum in Beijing, where it is now preserved.

"I hope it will be kept well, to tell future generations about that special bond in a special time," she said.