WASHINGTON - French and German scientists have found that the Sino-Tibetan language family originated about 7,200 years ago in what is now northern China.

This language family, one of the most diverse with more than 400 modern languages spoken by about 1.5 billion people, originated among millet farmers of Neolithic cultures, such as the late Cishan and early Yangshao. The findings were published on Monday in the journal Proceedings of the National Academy of Sciences.

In the past 10,000 years, two of the world's largest language families emerged, one in the West and one in the east of Eurasia, together accounting for nearly 60 percent of the world's population.

While the Indo-European language family has been examined comprehensively, the Sino-Tibetan one remains unclear. Some researchers assumed that it arose from southwestern China or northeastern India around 9,000 years ago.

The researchers assembled a lexical database containing core vocabulary from 50 Sino-Tibetan languages. This database includes ancient languages spoken 1,000 and more years ago, such as Old Chinese, Old Burmese and Old Tibetan, as well as modern languages documented by field work.

"We find clear evidence for seven major subgroups with a complex pattern of overlapping signals," says the paper's co-author, Simon Greenhill, of the Max Planck Institute for the Science of Human History. "Our estimates suggest that the ancestral language had arisen around 7,200 years ago."

The most likely expansion scenario of the languages involves an initial separation between an Eastern group, from which the Chinese dialects evolved, and a Western group, which is ancestral to the rest of the Sino-Tibetan languages, according to the researchers.

Another study published in the journal Nature on April 24 confirmed that Sino-Tibetan languages originated in present-day northern China, and this language family began to disperse and diversify around 5,900 years ago, a period associated with the Yangshao culture and later the Majiayao culture in the Yellow River basin.