Wuchang, Hankou, and Hanyang are the three cities. Why did they develop into cities here first?

The Yangtze River and the Han River divide Wuhan into three parts, which is what we often call the three towns of Wuhan. Wuchang is on the east side of the Yangtze River, and the west side of the Yangtze River is divided into two parts by the Han River. To the north of the Han River is Hankou, and to the south is Hanyang. Generally speaking, there are cities wherever there is water, not to mention where the Han River flows into the Yangtze River, a geomantic treasure, and the thoroughfare of nine provinces