China has half of the world's top 6 city clusters (a.k.a. megalopolises or megaregions): 1  The Pearl River Delta (Population: 120 million, including Guangzhou, Shenzhen, Dongguan, Hong Kong, Foshan, Zhuhai, and Macau). 2  The Yangtze River Delta (88 million, including Shanghai, Nanjing, Hangzhou, Ningbo, Suzhou).