The largest gene bank of Chinese ethnic minority groups has been set up at Yunnan University in southwest China's Yunnan Province, according to sources with university.

A total of 1,250 healthy male DNA samples from all 25 minority ethnic groups in Yunnan have been collected by the gene bank, according to Xiao Chunjie, director of the Human Genetics Studies Center with Yunnan University, based in Kunming, capital of Yunnan.

According to Xiao, 50 samples were taken from each of the 25 minority groups with a population of more than 5,000.

"It took us four years to collect these samples, all gathered in light of international standards," he said.

To get highly pure DNA samples, the collectors sampled from remote areas in deep mountains where minority ethic groups reside, he said.

"The reason why only male samples were collected is that men have both X and Y chromosomes, but women just have the Y chromosome," he said, adding that the sampled men have no relationship of consanguinity to each other.

In addition, at least three preceding generations of the sampled men were purely of the bloodline of their own ethnic groups, with no history of intermarriage with other groups, he said.

Yunnan is one of the birthplaces of the Chinese nation. Yuanmou Man is believed to have lived there about 1.7 million years ago. The fossils of Yuanmou Man were first discovered at the Shangnabang Village in Yuanmou County in 1965 by young geologist Qian Fang.

Currently, 25 out of China's 55 minority ethnic groups live in Yunnan, with a total population of more than 10 million. Among these, 15 minority ethnic groups are exclusive to Yunnan.