The largest gene bank of Chinese ethnic minority groups has recently been set up at Yunnan University in Southwest China's Yunnan Province.

A total of 1,250 healthy male DNA samples from all 25 minority ethnic groups in Yunnan have been collected by the bank, experts said.

Experts from the university said that 50 samples were taken from each of the 25 minority groups. Every minority group has a population of at least 5,000.

All the samples are stored in the university's gene bank, which is the world's largest minority group DNA information base, in both variety and quantity.

It took experts four years to collect the samples, and international standards were followed throughout the procedure, said Xiao Chunjie, director of the Human Genetics Studies Centre with Yunnan University, based in Kunming, capital of the province.

To get particularly pure samples, the people who gave DNA all live in remote areas, he said.

The qualifications of the donors is that they must have a pure bloodline for at least three generations, with no history of intermarriage with other ethnic groups, he said.

In addition, the sampled men must have no relationship with each other.

"The reason why only male samples were collected is that men have both X and Y chromosomes, while women just have X chromosomes," he said.

Experts believe that the bank will aid scientific research into gene variety and hereditary diseases among minority nationalities.

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 Shangnabang Village in Yuanmou County in 1965.

Currently, 25 out of China's 55 minority ethnic groups live in Yunnan, including the Yi, Bai and Hani. Fifteen of the groups are exclusive to the province, and the total minority population there is 10 million.