Yaoheyuan relics in Pengyang, Ningxia Hui autonomous region -- Western Zhou Dynasty (c. 11th century-771 BC). The photo shows a jade phoenix ornament found at the Yaoheyuan site. [Photo provided to China Daily]

Excavation of the Yaoheyuan ruins in Pengyang county, Northwest China's Ningxia Hui autonomous region, showed that this region might have been under the imperial rule of Chinese emperors much earlier than archaeologists previously thought.