"Phytolith analysis of residue found at the Dongyang site can help separate different tissues of the plants so as to analyze the farming conditions in a specific age," said Wu Yan, research associate of the Chinese Academy of Sciences Institute of Vertebrate Paleontology and Paleoanthropology.

"We also found phytoliths of rice leaves, husks and straws, a complete chain of rice-growing," she added.

Xu Weihong, a researcher with the Shaanxi Provincial Institute of Archaeology, said "Research indicates that rice comes from local farming rather than from trade or exchange."