禹貢
The "Yu Gong" ["Tribute of Yu"] records: "The Sea, Mount Dai (ancient name of Mount Tai), and the Huai River served as the boundaries of Xuzhou." While the definition of Xuzhou is more brief in "Erya": "Where is located in the east of Ji River". Based on these descriptions, the ancient Xuzhou covered an area that roughly corresponds to the regions in modern southeastern Shandong (south of Mount Tai) and northern Jiangsu (north of the Huai River).