The 1.16 billion Han Chinese, the world's biggest ethnic group, owe their rise thanks to massive southward migration from northern China led by the men of their tribe, according to a new study.
Chinese tradition says that the Han sprung from the ancient Huaxia communities of northern China and that their influence then spread south.
But the question is whether this was a migration of people or simply a cultural export -- whether the Han language, beliefs and other values were adopted by static communities who then handed it on to their southerly neighbours.
Genetic sleuthing by Chinese researchers may have found the answer.
Scientists led by Li Jin of Shanghai's Fudan University took blood samples from 871 individuals living in 17 communities across China.
They analysed the blood for telltale sequences in the Y chromosome, which only males have, and for variations of mitochondrial DNA, which is only handed down by women.
Little difference was found in the Y-chromosome fingerprint, but there were broad variations in the mitochondrial sequences. In other words, there was a clear Han lineage, determined by the males who initially came out of the north.
These men crossed the Yangtze River that until some 2,000 years ago was the country's ethnic divide. They then fanned out, progressively heading to the southwest, the southeast and due south, eventually colonising the tropical island of Hainan.
Li's team says the genetic evidence supports historical records which point to "continuous southward movements" of the Han due to warfare and famine in the north.
In the past two millennia, there have been three big migratory waves that pushed progressively further southwards, in AD 265-316, in 618-907, and in 1127-1279, with smaller migrations in between, according to the evidence from ancient scrolls and tablets.
"Our genetic observation is thus in line with the historical accounts," Li's team writes in Thursday's issue of Nature, the weekly British science journal.
"The massive movement of the northern immigrants led to a change in genetic makeup in southern China, and resulted in the demographic expansion of Han people as well as their culture."
In addition, gene flow between northern Hans, southern Hans and southern natives, also contributed to the genetic mix which shapes the distinctive genetic profile of China's populace today.
