Huai in Huaisi refers to Huai River (ancient Huai River), and Si refers to the ancient Sishui River. After checking, the Huaisi area roughly refers to the area with a radius of 200 kilometers centered on Xuzhou, Jiangsu (in ancient times, Pengcheng). The Xuzhou area happens to be the junction of the four provinces of Anhui, Henan, Jiangsu, and Shandong. This area also happens to be the current dividing line between north and south in China.

The Huaisi area is located in the lower reaches of the Huaihe River and is the natural dividing line between the north and the south of China. The Huaisi area is mainly divided into two parts, which belong to the Haizhou and Sizhou areas in the north in the traditional sense and the Chuzhou area in the south in the traditional sense. The Huaisi region is located in the watershed area between southern and northern China.