1.5m Chinese 'descendants of one man'

Giocangga's extraordinary number of descendants, concentrated mainly in north-east China and Mongolia, are thought to be a result of the many wives and concubines his offspring took.

Dr Chris Tyler-Smith, a geneticist working at Britain's Wellcome Trust Sanger Institute, made the finding, based on a study of a set of genes on the male Y chromosome.

He told the BBC World Service's Science In Action programme that these genes provided a "genetic surname" of the family to which each man belonged.

"What we did was analyse around 1,000 men from that part of the world," he said.

"We noticed just two types of Y chromosome that were extraordinarily frequent - one of them making up around 3% of our sample.

"When we looked at it more carefully, we found that it was not present in the majority population in that area, the Han. But in the minorities, including the Mongolians, it was present at around 5%."

'Good chance of survival'

Scientists were then able to work out roughly where the special genes came from.

They established the origin was north-east China, around 500 years ago.

More accurate analysis then found that this particular genetic code first appeared just before the Qing dynasty, which came to the fore in 1616 and had conquered China by 1644.

"We soon realised there was a major historical event going on at this time - the establishment of the Qing dynasty, which conquered China and ruled for several hundred years," Dr Tyler-Smith said.

"It was ruled by the Qing imperial nobility, who were a highly privileged elite class, and they had several wives and concubines.

"Because of the privilege, they could have had many children - and those children would have had a good chance of survival."

At the time of Giocangga, the population of China was about 100 million - compared with 1.3 billion today.

This means that the average Chinese man at the time of Giocangga would only have around 20 descendants living today - in marked contrast to Giocangga's 1.5 million men.

"The difference is accounted for by the large number of wives and concubines - and in particular, this practice being linked to the Y chromosome for many generations," Dr Tyler-Smith added.