Latest archaeological discoveries show that wheat was introduced to central China some 4,000 years ago, earlier than previously believed.

Carbonized wheat grain, dated back to 4,000 years ago, has been found in the Jiaochangpu relics site in east China's Shandong Province, Zhao Zhijun, a researcher with the Institute of Archaeology of the Chinese Academy of Social Sciences, told Xinhua on Sunday.

Previously, archaeologists had found 3,600-year-old carbonized wheat in the site in Luoyang, central China's Henan Province.

"It's believed that wheat was spread to China along a route from west to east. Since the Jiaochangpu relics site is located to the east of central China, wheat should have entered central China earlier than 4,000 years ago," Zhao said.

Grains of carbonized wheat have also been found in relics sites from the Xia, Shang and Zhou dynasties dating from 3,000 to 2,000 years ago, in central China, including at the Erlitou, Yanshi and Yin ruins.

"Those findings indicate that wheat was quickly popularized after it entered central China," Zhao said.

Li Shuicheng, a professor with the archaeology department of Beijing University, said that wheat originated about 10,000 years ago in west Asia, and spread to Europe, north Africa and central Asia during the period between 8,500 to 7,500 years ago.

A large number of wheat remains have recently been discovered in China, mainly in Xinjiang Uygur Autonomous Region and provinces of Gansu, Qinghai, Shaanxi and Henan, said Li.

Dating of the carbonized wheat grains showed that those found in the western region were older than those in the east, indicating a spreading route from west to east, said Li.

Zhao Zhijun said since wheat originated in west Asia, it has not yet entirely adapted to the climate of China. Wheat needs water in the spring, a dry season in north China.

Therefore, construction of an irrigation system became the key for planting wheat at a large scale in north China, said Zhao.

Before wheat entered China, the staple food in north China was millet. The output of wheat is several times that of millet. The replacement of millet by wheat is regarded as an agricultural revolution in north China, Zhao added.

(Xinhua News Agency October 10, 2005)