Photo taken on April 23, 2013 shows pottery pieces discovered at a newly discovered ancient workshop site in Zibo, east China's Shandong Province. A bronze mirror workshop, dating from some 2,000 years ago in China's Han Dynasty (202 B.C.-220 A.D.), was discovered in Zibo and believed to be the first of its kind discovered in China. Photo: Xinhua

Archeological workers work at at a newly discovered ancient workshop site in Zibo, east China's Shandong Province, April 23, 2013. A bronze mirror workshop, dating from some 2,000 years ago in China's Han Dynasty (202 B.C.-220 A.D.), was discovered in Zibo and believed to be the first of its kind discovered in China. Photo: Xinhua

Archeological workers work at at a newly discovered ancient workshop site in Zibo, east China's Shandong Province, April 23, 2013. A bronze mirror workshop, dating from some 2,000 years ago in China's Han Dynasty (202 B.C.-220 A.D.), was discovered in Zibo and believed to be the first of its kind discovered in China. Photo: Xinhua