How does the Yangtze River divide Jiangsu province?

The Yangtze River serves as a primary geographic divider for Jiangsu province, splitting it into two distinct sections:1

• Jiangnan: Located south of the river, this name literally translates to "South of the River." It is a fertile, well-watered, and highly industrialized region known for its silk production and dense population. Major cities such as Nanjing, Suzhou, and Wuxi are situated here.1
• Subei: This region, meaning "North [Jiang]su," encompasses the area north of the Yangtze. It is generally less wealthy than Jiangnan and includes the Yangtze-Huai plain and the Xuzhou-Huai plain.12

While the Yangtze acts as a major landmark, geographers also use the ancient channel of the Huai River to further divide the province's plains into three sections: the Jiangnan plain, the Yangtze-Huai plain (between the Yangtze and the old Huai channel), and the Xuzhou-Huai plain (north of the old Huai channel).2