Go to the west entrance, travel to the east of Guandong, and sail to Nanyang. What is the missing word?

The three major feats in the history of Chinese national migration: crossing the Guandong, taking the west entrance, and sailing to Nanyang. The next one should be Beijing, Shanghai and Guangzhou.

Beijing, Shanghai and Guangzhou originally referred to the abbreviations of China's first-tier cities Beijing, Shanghai, and Guangdong (Guangzhou and Shenzhen), but gradually they are also used to refer to modern metropolises with extremely high survival costs.