Liang Jinsheng could have been retired for seven years, but he still rides his bicycle three hours everyday between his home and office in the Forbidden City. There, he carefully documents the cultural relics that failed to return to Beijing after the War Against Japanese Aggression (1931-1945).

"We should make history clear for the next generation," says the 67-year-old former head of the Palace Museum' s cultural relics administration department.

In September 1931, the Japanese army invaded northeast China, and Beijing was on the edge of being occupied. To prevent relics from being looted and damaged, the government decided to move the antiques of the Forbidden City southwards under a military escort.

On Feb. 6, 1933, after a year of hurried packing, a group of museum staff and soldiers set out with 13,427 boxes of relics. Three months later, they arrived in Shanghai, and then moved to the neighboring city of Nanjing, capital of the Kuomintang (KMT) government, in 1936.

However, the flames of the war soon came there after the Battle of Shanghai, one of the bloodiest battles in China. The convoy split into three teams: one headed farther south to Guizhou Province; one southwest to mountainous Sichuan Province; and the last northwest at first and then southwest through Sichuan, near the provisional capital of Chongqing.

The journey was consistent with the government's retreat route, Liang says. "Despite some objections, it was part of the national strategy in the War Against Japanese Aggression."

It was also personal journey for those involved - and it continued for decades after. Liang's grandparents, father and uncles all traveled with the relics. Liang and his siblings were born along the way.

In 1945, the Japanese army surrendered, and the three teams brought all the relics back to Nanjing over the next two years, ending their 15-year southward migration.