Why are the Wu dialect areas in Jiangsu, Zhejiang and Shanghai generally so developed?

Since the ancient Beijing-Hangzhou Grand Canal, it is more convenient for northern residents to enter the south. The Yangtze River Delta has fertile land, mild climate, dense water network and convenient agriculture and transportation. After the Song Dynasty, the north was not very stable, and Jiangsu and Zhejiang became the main sources of central finance. The emergence of capitalism in Ming and Qing Dynasties further developed the silk industry. At that time, Yangzhou, Nanjing and Suzhou in the south of the Yangtze River were all first-class cities, and Jiangsu and Zhejiang regions were becoming more and more important to the central finance. Among them, Suzhou paid the highest tax in the country in the late Ming Dynasty, nearly three times more than Songjiang. Later, Shanghai opened its port in modern times and developed rapidly into a metropolis. At that time, Jiangsu and Zhejiang all conducted foreign trade through Shanghai. After the reform and opening up, Shanghai has become a window to the outside world. Many foreign companies have entered Jiangsu and Zhejiang through Shanghai, and the prosperity of township enterprises has promoted the prosperity of Jiangsu, Zhejiang and Shanghai.