SHANGHAI, April 19 (Xinhua) -- A sixty-volume compendium documenting more than 23,000 ancient Chinese bronze artifacts lost abroad was published on Sunday by Shanghai Classics Publishing House.

The books' publication marks China's first systematic investigation and sorting of the status of important bronze cultural relics scattered overseas.

The project began in 2012, when China's National Cultural Heritage Administration entrusted Peking University to assess the scale of the country's lost cultural relics.

Led by Professor Zhu Fenghan, the university's research team visited more than 260 institutions across over 10 countries to trace the scattered relics and related records, while also visiting collectors.

Zhu, also the lead editor of the books, said previous such surveys focused mainly on bronze bells, cauldrons and ritual vessels. This collection categorizes nearly 300 types of bronze artifacts, ranging from weapons, tools, lamps and mirror stands to irons, coal rakes and dice. One example is a human-shaped lamp stand currently at the Minneapolis Institute of Art.

Previously, scholars at home and abroad generally assumed that there were over 3,000 Chinese bronze wares in overseas collections. However, the "Collection of Chinese Bronzes in Overseas Collections" has expanded this figure by more than sevenfold.

"We have created an identity document for each piece of relics," Zhu said. The team found that only a few relics have clear records of legal trade, diplomatic gifts or legitimate export.

As the compendium points out, the primary channels for these bronzes leaving China from the late 19th century to mid-20th century were looting, smuggling and war plunder. Western collectors and dealers bought large numbers through agents inside China, forming an illegal supply chain.

Speaking at the press conference for the books' release, Zhu Ye, deputy director of the exchange department of the National Cultural Heritage Administration, called bronzes a core symbol of Chinese civilization. The compendium, she said, creates a cross-regional, traceable database that could support future recovery efforts.

Chinese cultural relics experts are generally concerned that the so-called absence of "chain of evidence" is the biggest bottleneck for recovery. Ge Liang, a bronze expert at the Shanghai Museum in east China, explained that it is difficult to find evidence to confirm "illegal acquisition."

Duan Yong, director of the Center for Research on Chinese Cultural Relics Abroad at Shanghai University, said China should pursue the return of bronzes and other relics step by step, focusing on priorities and rational negotiation.