In 1929, a peasant in Sichuan province uncovered jade and stone artifacts while repairing a sewage ditch located about 24 miles (40 kilometers) from Chengdu. But their significance wasn't understood until 1986, when archaeologists unearthed two pits of Bronze Age treasures, such as jades, about 100 elephant tusks and stunning 8-feet-high (2.4 meters) bronze sculptures that suggest an impressive technical ability that was present nowhere else in the world at the time, said Peter Keller, a geologist and president of the Bowers Museum in Santa Ana, California, which is currently hosting an exhibit of some of these treasures.

The treasures, which had been broken and buried as if they were sacrificed, came from a lost civilization, now known as the Sanxingdui, a walled city on the banks of the Minjiang River.

Archaeologists now believe that the culture willfully dismantled itself sometime between 3,000 and 2,800 years ago, Fan said.

"The current explanations for why it disappeared are war and flood, but both are not very convincing," Fan told Live Science.

— Tia Ghose, Live Science

This is a abbreviated version of a report from Live Science. Read the full report. Follow Tia Ghose on Twitter and Google+. Follow LiveScience @livescience, Facebook & Google+.

More from Live Science: