The photo shows the excavation site of Jiren Taigoukou Ruins in Qialege'e village in Nilka county in Ili Valley, Northwest China's Xinjiang Uygur autonomous region. Archaeologists have unearthed evidence of coal being burned on the ancient site dating back to the Bronze Age, about 3,500 years ago, according to Xinjiang Institute of Archaeology on November 1, 2016. The new findings mean that humans were using coal about 1,000 years earlier than previously thought. (Photo: Photo provided to China News Service)