Introduction to Yiyuan: Yiyuan County is affiliated to Zibo City. It is named because the Yi River, the longest inland river in the province, originates here. Yiyuan County is the birthplace of ancient humans in Shandong, the ecological highland on the roof of Shandong, the hometown of karst caves and the Cowherd and the Weaver Girl in northern China. It has both natural and cultural landscapes and is a tourist attraction.